REGISTRATION RIGHTS AGREEMENT

Exhibit 10.10

EXECUTION COPY

REGISTRATION RIGHTS AGREEMENT

dated as of December 9, 2003

between

GLOBAL CROSSING LIMITED,

and

STT CROSSING LTD

TABLE OF CONTENTS

i

THIS REGISTRATION RIGHTS AGREEMENT (this “ Agreement ”) is made and entered into as of December 9, 2003, by and among Global Crossing Limited (formerly GC Acquisition Ltd.), a company organized under the laws of Bermuda (the “ Company ”), and STT Crossing Ltd, a company organized under the laws of Mauritius (“ Purchaser ”), and each other person who becomes a Holder (as defined below) hereunder.

RECITALS

WHEREAS, the parties hereto have entered into a Purchase Agreement by and among Global Crossing Ltd. (“ GX ”), Global Crossing Holdings Ltd., the Joint Provisional Liquidators, Singapore Technologies Telemedia Pte Ltd (“ ST Telemedia ”) and Hutchison Telecommunications Limited, dated August 9, 2002 (as amended, supplemented or otherwise modified from time to time, the “ Purchase Agreement ”), pursuant to which, among other things, Purchaser will acquire 6,600,000 shares of the Company’s Common Stock, par value $.01 per share (the “ Common Shares ”), and 18,000,000 shares of the Company’s 2.0% Cumulative Senior Convertible Preferred Stock, par value $.10 per share (the “ Preferred Shares ”);

WHEREAS, to induce ST Telemedia to execute and deliver the Purchase Agreement and consummate the transactions contemplated thereby, GX has agreed to cause the Company to provide to Holder certain registration rights under the Securities Act (as defined below); and

WHEREAS, the execution and delivery of this Agreement by the parties hereto is a condition to the closing of the transactions contemplated by the Purchase Agreement.

NOW, THEREFORE, in consideration of the mutual promises and agreements set forth herein and in the Purchase Agreement, and for other valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto agree as follows:

Section 1. Definitions . For purposes of this Agreement, capitalized terms used but not defined herein shall have the meanings specified in the Purchase Agreement. In addition, the following capitalized terms have the following meanings:

“ Exchange Act ”: The United States Securities Exchange Act of 1934, as amended, or any successor federal statute, and the rules and regulations of the SEC thereunder, all as the same shall be in effect from time to time. Reference to a particular section of the Exchange Act shall include reference to a comparable section, if any, of any such successor federal statute.

“ Holder ”: Purchaser and its transferees to whom Purchaser agrees to assign benefits or rights under this Agreement and who agree to be bound by the provisions of this Agreement in accordance with Section 9(e) hereof; provided , however , that for purposes of all provisions of this agreement insofar as they relate to the making of any decision, determination, approval or consent or the giving of any notice by Holder (including any such decision or notice concerning the exercise of any rights of Holder hereunder), Holder shall mean only Purchaser.

“ Person ”: Any individual, partnership, limited liability company, joint venture, corporation, association, trust or any other entity or organization.

1

“ Prospectus ”: The prospectus included in any Registration Statement (including, without limitation, a prospectus that discloses information previously omitted from a prospectus filed as part of an effective registration statement in reliance upon Rule 430A under the Securities Act), as amended or supplemented by any prospectus supplement, with respect to the terms of the offering of any portion of the Registrable Securities covered by such Registration Statement and all other amendments and supplements to such prospectus, including post-effective amendments, and all material incorporated by reference or deemed to be incorporated by reference in such prospectus.

“ Registrable Securities ”: Common Shares, Common Shares or other securities which Holder may acquire upon conversion of the Preferred Shares, together with (a) any other securities which such Holder may acquire on account of any such securities, including, without limitation, as the result of any dividend or other distribution on Common Shares or any subdivision of such Common Shares or in connection with any combination of shares, recapitalization, amalgamation, merger, consolidation or reorganization or otherwise, and (b) any additional Common Shares which such Holder has acquired prior to the date hereof, or may acquire from time to time within the first three years after the date hereof, whether or not such Common Shares are acquired from the Company or any other person or entity (collectively, “ Other Acquired Common Shares ”); provided that a security ceases to be a Registrable Security (i) when it is no longer a Transfer Restricted Security, or (ii) if it is an Other Acquired Common Share which was not acquired from the Company and is transferred to a Person that is not an affiliate (as defined in Rule 12b-2 of the Exchange Act) of Holder.

The number of shares of “Registrable Securities” outstanding shall be determined by the number of Common Shares outstanding that are, and the number of Common Shares issuable pursuant to then exercisable or convertible securities that are, Registrable Securities.

“ Registration Statement ”: Any registration statement of the Company under the Securities Act that covers any of the Registrable Securities pursuant to the provisions of this Agreement, including the related Prospectus, any preliminary prospectus, all amendments and supplements to such registration statement (including post-effective amendments), all exhibits and all material incorporated by reference or deemed to be incorporated by reference in such registration statement.

“ Rule 144 ”: Rule 144 promulgated under the Securities Act, and any successor provision thereto.

“ Securities Act ”: The Securities Act of 1933, as amended, or any successor federal statute, and the rules and regulations of the SEC thereunder, all as the same shall be in effect at the time. Reference to a particular section of the Securities Act shall include reference to the comparable section, if any, of such successor federal statute.

“ SEC ”: The United States Securities and Exchange Commission and any successor governmental entity.

“ Transfer Restricted Securities ”: The Registrable Securities, until the date on which (i) such Registrable Securities are effectively registered under the Securities Act and

2

disposed of pursuant to such effective registration statement, (ii) such Registrable Securities are sold by a Person in a transaction in which the rights under the provisions of this Agreement are not assigned, (iii) such Registrable Securities are sold pursuant to Rule 144 (or any similar provision then in force, but not Rule 144A) under the Securities Act without registration under the Securities Act, or (iv) the entire amount of the Registrable Securities may, in the opinion of counsel satisfactory to the Company and Holder, be sold by Holder pursuant to Rule 144 (or any successor provision then in effect) under the Securities Act in a single sale without any limitation as to volume.

“ Underwritten Offering ”: A distribution, registered pursuant to the Securities Act, in which securities of the Company are sold to the public through one or more underwriters.

Section 2. Demand Registration

(a) Requests for Registration . At any time commencing on or after the date that is 180 days following the Closing Date, Holder will have the right, by written notice delivered to the Company (a “ Demand Notice ”), to require the Company to register Registrable Securities under and in accordance with the provisions of the Securities Act (a “ Demand Registration ”); provided, that, (i) Holder may not make more than four Demand Registrations, (ii) the aggregate offering price (net of underwriters’ discounts and commissions) of the Registrable Securities requested by Holder to be so registered must exceed $25,000,000, and (iii) Holder must provide to the Company a certificate (the “ Authorizing Certificate ”) signed by Holder; and provided , further , that no Demand Notice may be given by Holder prior to six months after the effective date of the immediately preceding Demand Registration. For purposes of the preceding sentence, the filing of two or more Registration Statements in response to one demand shall be counted as one Demand Registration. Each request for a Demand Registration by Holder shall state the amount of the Registrable Securities proposed to be sold and the intended method of disposition thereof. The Authorizing Certificate shall set forth (A) the name of Holder signing such Authorizing Certificate, (B) the number of Registrable Securities held by such Holder and the number of Registrable Securities such Holder has elected to have registered, and (C) the intended methods of disposition of the Registrable Securities. Holder may at its option withdraw Registrable Securities from a registration and, in such event (1) any continuing registration of Registrable Securities shall constitute the Demand Registration to which Holder is entitled and (2) the withdrawing Holder shall reimburse the Company for any registration and filing fees (including any fees payable to the SEC, the National Association of Securities Dealers, Inc. or any successor organization) it has incurred with respect to the withdrawn Registrable Securities (unless all Registrable Securities are withdrawn, in which case the withdrawing Holder shall reimburse the Company for all costs and expenses incurred by it in connection with the registration of such Registrable Securities). Subject to compliance with clause (2) of the preceding sentence, a registration that is terminated in its entirety prior to the effective date of the applicable Registration Statement will not constitute a Demand Registration. Notwithstanding the foregoing, if at the time of withdrawal, Holder has learned of a material adverse change in the condition, business or prospects of the Company and has withdrawn the request with reasonable promptness following disclosure by the Company, Holder shall not be subject to clause (2) above.

3

If a Demand Registration is not declared and maintained effective for the period required by Section 2(b) or if the consummation of the offering of Registrable Securities pursuant to such Demand Registration (A) is interfered with by any stop order, injunction or other order or requirement of the SEC or other governmental agency or court for any Person which is not directly caused by the act or omission of any Holder and such act or omission is not thereafter eliminated or (B) the conditions specified in the underwriting agreement with respect to an Underwritten Offering, if any, entered into in connection with such Demand Registration are not satisfied or waived, other than by reason of a failure by Holder, then Holder shall be entitled to an additional Demand Registration in lieu thereof.

(b) Filing and Effectiveness . (i) The Company will file or, if permitted, submit confidentially, a Registration Statement relating to any Demand Registration as promptly as practicable (but in any event within 45 days in the case of a registration made on Form S-1 or F-1, or a comparable successor form, as applicable, or 30 days in the case of any registration eligible to be made on Form S-3 or F-3 or a comparable successor form, as applicable) following the date on which the Demand Notice is given and will use its reasonable best efforts to cause the same to be declared effective by the SEC as soon as practicable thereafter (the “ Effectiveness Date ”).

(ii) The Company agrees to use its reasonable best efforts to comply with all necessary provisions of the federal securities laws in order to keep each Registration Statement relating to a Demand Registration effective for a period of (A) in the case of an Underwritten Offering, 120 days from its Effectiveness Date, and (B) subject to the last proviso of this clause (ii), in the case of any registration made pursuant to Rule 415 under the Securities Act, twenty-four (24) months from its Effectiveness Date, or such shorter period that will terminate when all Registrable Securities covered by such Registration Statement have been sold pursuant to such Registration Statement (in each case, such period being the “ Effectiveness Period ”); provided , however , that if any Black-Out (as hereinafter defined) occurs during an Effectiveness Period, then such Effectiveness Period will be tolled for the duration of the Black-Out.

Holder will be permitted, subject to its compliance with the provisions of Section 2(a) relating to reimbursement of the Company’s expenses, to withdraw in good faith all or part of the Registrable Securities from a Demand Registration at any time prior to the effective date of such Demand Registration, in which event the Company will promptly amend or, if applicable, withdraw the related Registration Statement.

(c) Priority on Demand Registration . Notwithstanding the foregoing, if the managing underwriter or underwriters of an Underwritten Offering to which such Demand Registration relates advises the Company and Holder in writing that the total amount of Registrable Securities that Holder, the Company and any other Person intend to include in such Demand Registration is in the aggregate such as to materially and adversely affect the success of such offering, then there will be included in such Demand Registration, (i) first, the number of securities that Holder proposes to sell pursuant to such Demand Registration, (ii) second, to the extent that the number of securities in clause (i) above is less than the number of securities which the Company and Holder have been advised can be sold in such offering without having the adverse effect referred to above, the number of securities, if any, requested to be included in such

4

offering by any other Persons pursuant to similar registration rights, determined pro rata on the basis of the number of shares of the class being sold owned by such other Persons requesting registration, collectively, and (iii) third, to the extent that the number of securities in clauses (i) and (ii) above is less than the number of securities which the Company and Holder have been advised can be sold in such offering without having the adverse effect referred to above, the securities, if any, sought to be included by the Company in the offering.

(d) Postponement of Demand Registration . Notwithstanding anything to the contrary in any other provision of this Agreement, the Company will be entitled, on no more than one occasion in any 12-month period, to postpone the filing period of any Demand Registration for a reasonable period of time not in excess of 120 calendar days if the Board of Directors of the Company determines, in the good faith exercise of its business judgment, and has delivered to Holder written certification to the effect, that such registration and offering would materially and adversely interfere with a bona fide financing transaction of the Company, including without limitation a primary offering of securities, or any other material business transaction of the Company, or would require disclosure of information, the premature disclosure of which would materially and adversely affect the Company. If the Company postpones the filing of a Registration Statement, it will promptly notify Holder in writing when the events or circumstances permitting such postponement have ended.

Section 3. Piggyback Registration and Form S-3 or F-3 Registration .

(a) Right to Piggyback . If, at any time following the Closing Date, the Company proposes to file a Registration Statement, whether or not for sale for the Company’s own account or for the account of a shareholder of the Company, on a form and in a manner that would also permit registration, offer or sale of Registrable Securities (other than the initial public offering of the capital stock of the Company and other than in connection with a registration statement on Forms S-4 or F-4 or S-8 or any similar or successor form), the Company shall each such time give to Holder holding Registrable Securities written notice of such proposed filing at least 20 days before the anticipated filing. The notice referred to in the preceding sentence shall (i) describe the proposed registration and offering and (ii) offer Holder the opportunity to register, offer or sell such amount of Registrable Securities as Holder may request (a “ Piggyback Registration ”). Subject to Section 3(b), the Company will include in each such Piggyback Registration (and any related qualification under state blue sky laws and other compliance filings, and in any underwriting involved therein) all Registrable Securities with respect to which the Company has received written requests for inclusion therein within 10 days after the written notice from the Company is given. Holder will be permitted, subject to its compliance with the provisions of Section 2(a) relating to reimbursement of the Company’s expenses, to withdraw all or part of its Registrable Securities from a Piggyback Registration at any time prior to the effective date of such Piggyback Registration.

(b) Priority on Piggyback Registrations . The Company will cause the managing underwriter or underwriters of a proposed Underwritten Offering to permit Holder, if holding Registrable Securities requested to be included in the registration for such offering, to include therein all such Registrable Securities requested to be so included (such securities, together with any other shares of the same class requested to be included in such registration by any other Person pursuant to similar registration rights, the “ Piggyback Shares ”) on the same terms and

5

conditions as any securities of the Company included therein (other than the indemnification by Holder, which will be limited as set forth in Section 6(b) hereof and provided , that Holder gives customary representations and warranties). The Company shall cooperate with Holder in order to limit any representations and warranties to, or agreements with, the Company or the underwriters to be made by Holder only to those representations, warranties or agreements regarding Holder, Holder’s Registrable Securities and Holder’s intended method of distribution and any other representation required by law. Notwithstanding the foregoing, if the managing underwriter or underwriters of such Underwritten Offering advises Holder in writing to the effect that the total amount of securities that Holder, the Company and any other Person propose to include in such Underwritten Offering is such as to materially and adversely affect the success of such offering, then the Company will include in such registration:

(x) in the case of a registration in connection with a sale of securities for the Company’s own account, (i) first, 100% of the securities that the Company proposes to sell for its own account, (ii) second, to the extent that the number of securities in clause (i) above is less than the number of securities which the Company has been advised can be sold in such offering without having the adverse effect referred to above, the number of Piggyback Shares of Holder requested to be included in such offering, and (iii) third, to the extent that the number of securities in clauses (i) and (ii) above is less than the number of securities which the Company has been advised can be sold in such offering without having the adverse effect referred to above, the number of Piggyback Shares requested to be included in such offering by any other Persons pursuant to similar registration rights, determined pro rata on the basis of the number of shares of the class being sold owned by such other Persons requesting registration, collectively; and

(y) in the case of a registration in connection with a sale of securities on account of any Person other than the Company or Purchaser (the “ Initiating Party ”), (i) first, 100% of the securities, if any, that the Initiating Party proposes to sell, (ii) second, to the extent that the number of securities in clause (i) above is less than the number of securities which the Company has been advised can be sold in such offering without having the adverse effect referred to above, the number of Piggyback Shares of Holder requested to be included in such offering, (iii) third, to the extent that the number of securities in clauses (i) and (ii) above is less than the number of securities which the Company has been advised can be sold in such offering without having the adverse effect referred to above, the number of Piggyback Shares requested to be included in such offering by any other Persons pursuant to similar registration rights, determined pro rata on the basis of the number of shares of the class being sold owned by such other Persons requesting registration, collectively, and (iv) fourth, to the extent that the number of securities in clauses (i) through (iii) above is less than the number of securities which the Company has been advised can be sold in such offering without having the adverse effect referred to above, the securities sought to be included by the Company in the offering.

(c) Form S-3 or F-3 Registration . At any time after the Company becomes eligible to use Form S-3 or F-3 (or any successor form then in effect), Holder may make a written request that the Company effect a registration on Form S-3 or F-3 (or any successor form then in effect) and any related qualification or compliance with respect to all or a part of the Registrable Securities owned by Holder, and the Company will use its reasonable best efforts to

6

effect such registration and all such qualifications and compliances as may be so requested and as would permit or facilitate the sale and distribution of all or such portion of Holder’s Registrable Securities as are specified in such request; provided , however , that the Company shall not be obligated to effect any such registration, qualification or compliance, pursuant to this Section 3(c): (i) if Form S-3 or F-3 (or any successor form then in effect), is not available for such offering by Holder; (ii) if Holder, together with the holders of any other securities of the Company entitled to inclusion in such registration, propose to sell Registrable Securities and such other securities (if any) at an aggregate price to the public (net of any underwriters’ discounts or commissions) of less than $25,000,000; (iii) if the Board of Directors of the Company determines, in the good faith exercise of its business judgment, and has delivered to Holder written certification to the effect, that such registration and offering would materially and adversely interfere with a bona fide financing transaction of the Company, including any material business transaction of the Company, or would require disclosure of information, the premature disclosure of which would materially and adversely affect the Company, in which event the Company shall have the right to defer the filing of the Form S-3 or F-3 Registration Statement for a period of not more than 120 calendar days after receipt of the request of Holder under this Section 3(c); provided , however , that if the Company postpones the filing of a Form S-3 or F-3 Registration Statement, it will promptly notify Holder in writing when the events or circumstances permitting such postponement have ended; and provided , further , that the Company will be entitled to utilize this right on no more than one occasion in any 12-month period. An underwritten registration on Form S-3 or F-3 effected pursuant to this Section 3(c) shall be counted as a Demand Registration for purposes of determining the number of Demand Registrations granted under Section 2. Any other registration under this Section 3 shall not count as a Demand Registration.

Section 4. Registration Procedures . In connection with the Company’s registration obligations pursuant to Sections 2 and 3, the Company will effect such registrations to permit the sale of such Transfer Restricted Securities in accordance with the intended method or methods of disposition thereof, and pursuant thereto the Company will as expeditiously as possible, and in each case to the extent applicable:

(a) Prepare and file with the SEC a Registration Statement or Registration Statements on any appropriate form under the Securities Act available for the sale of the Registrable Securities by the holders thereof in accordance with the intended method or methods of distribution thereof, and cause each such Registration Statement to become effective and remain effective as provided herein; provided , however , that (i) before filing a Registration Statement or Prospectus or any amendments or supplements thereto (including documents that would be incorporated or deemed to be incorporated therein by reference) the Company will furnish to Holder holding Registrable Securities covered by such Registration Statement, not more than one counsel chosen by Holder (“ Special Counsel ”) and the managing underwriters, if any, copies of all such documents proposed to be filed, which documents will be subject to the review and comment of Holder, such Special Counsel and such underwriters, and the Company will not file any such Registration Statement or amendment thereto or any Prospectus or any supplement thereto (excluding such documents that, upon filing, will be incorporated or deemed to be incorporated by reference therein) to which Holder or the managing underwriter, if any, shall reasonably object, and (ii) the Company shall notify the Special Counsel and each seller of Registrable Securities of any stop order issued or threatened by the SEC and take all action required to prevent the entry of such stop order or to remove it if entered.

7

(b) Prepare and file with the SEC such amendments and post-effective amendments to each Registration Statement as may be necessary to keep such Registration Statement continuously effective for the applicable periods specified in Section 2; cause the related Prospectus to be supplemented by any required Prospectus supplement, and as so supplemented to be filed pursuant to Rule 424 (or any similar