<PAGE>

                                                                   EXHIBIT 10.55

                                                                  EXECUTION COPY

                             Dated 17 September 2004

                    HTHK LIMITED                                        (1)

                    HUTCHISON TELECOMMUNICATIONS                        (2)
                    LIMITED

                         -------------------------------

                           SALE AND PURCHASE AGREEMENT

                                   relating to

                     HUTCHISON MOBILE COMMUNICATIONS LIMITED

                         -------------------------------

<PAGE>

THIS AGREEMENT is made the 17th day of September 2004

BETWEEN:

1.   HTHK LIMITED, a company incorporated with limited liability in the British
     Virgin Islands whose registered office is at P.O. Box 957, Offshore
     Incorporations Centre, Road Town, Tortola, British Virgin Islands (the
     "Vendor"); and

2.   HUTCHISON TELECOMMUNICATIONS LIMITED, a company incorporated with limited
     liability in Hong Kong whose registered office is at 22nd Floor, Hutchison
     House, 10 Harcourt Road, Hong Kong (the "Purchaser").

WHEREAS:-

A.   HUTCHISON MOBILE COMMUNICATIONS LIMITED (the "Company") (Registration
     Number 559134) is a company incorporated under the laws of the British
     Virgin Islands with limited liability, further particulars of which are set
     out in the Schedule.

B.   The Vendor is the beneficial owner and registered holder of the Sale
     Shares.

C.   The Vendor wishes to sell to the Purchaser, and the Purchaser wishes to
     purchase from the Vendor, the Sale Share on the terms and subject to the
     conditions set out herein.

NOW IT IS HEREBY AGREED as follows:

1.   DEFINITIONS AND INTERPRETATION

1.1  In this Agreement (including the Recitals and the Schedule), the words and
     expressions set out below shall have the respective meanings attributed to
     them below unless the context otherwise requires:-

     "Business Day"    a day on which banks are open for business in Hong Kong
                       (excluding Saturday or Sunday);

     "Completion"      completion of the sale and purchase of the Sale Shares
                       in accordance with the terms and conditions of this
                       Agreement;

     "Consideration"   US$1.00;

     "Hong Kong"       the Hong Kong Special Administrative Region of the
                       People's Republic of China;

     "Sale Share"      one share of US$1.00 in the Company; and

<PAGE>

     "US$"             United States dollars, the lawful currency of the
                       United States of America.

1.2  Unless the context otherwise requires, words importing the singular only
     shall include the plural and vice versa and words importing natural persons
     shall include corporations and unincorporated associations and vice versa.

1.3  The descriptive headings contained in this Agreement are for the purpose of
     convenience only and do not form part of and shall not affect the
     construction of this Agreement or any part thereof.

1.4  References to Clauses and the Schedule are to the clauses of and the
     schedule to this Agreement and references to sub-clauses, paragraphs and
     sub-paragraphs are to sub-clauses of the Clauses, paragraphs of the
     sub-clauses and sub-paragraphs of the paragraphs where they respectively
     appear.

1.5  Reference to any statute or statutory provision shall where the context so
     admits or requires be construed as reference to those provisions as
     respectively amended, consolidated, extended, modified or re-enacted from
     time to time, and shall include any other order, regulations, instruments
     or other subordinate legislation made under the relevant statute.

1.6  The Schedule forms an integral part of this Agreement and shall have the
     full force and effect as if expressly set out in the body of this Agreement
     and any reference to this Agreement shall, unless the context otherwise
     requires, include the Schedule.

2.   SALE AND PURCHASE

2.1  Upon and subject to the terms and conditions of this Agreement, the Vendor
     as legal and beneficial owner of the Sale Share, shall sell or procure the
     sale of, and the Purchaser shall purchase, the Sale Share free from all
     claims, charges, liens, options, encumbrances and equities of any kind
     whatsoever but together with all rights attached, accrued or accruing
     thereto and all dividends and distributions declared, made or paid or
     agreed to be made or paid thereon after the date hereof.

2.2  The total consideration for the sale of the Sale Share shall be an amount
     equal to US$1.00. Payment of the Consideration shall be made by the
     Purchaser by wire transfer or such other way as the parties may agree.

3.   COMPLETION

3.1  Completion shall take place simultaneously with the signing of this
     Agreement at 22nd Floor, Hutchison House, 10 Harcourt Road, Hong Kong or at
     such other place or time

<PAGE>

     as the parties hereto may agree, when all (but not part only) of the
     businesses set out in Clauses 3.3 to 3.4 shall be transacted.

3.2  On or before Completion, the Vendor shall procure that a board meeting of
     the Company is held at which resolutions shall be passed approving the
     registration of the transfer of the Sale Share to the Purchaser.

3.3  At Completion, the Vendor shall deliver or procure to be delivered to the
     Purchaser:

     (a)  share certificate for the Sale Share in the name of the Vendor or its
          nominee;

     (b)  instrument of transfer executed by the Vendor in relation to the Sale
          Share in favour of the Purchaser;

     (c)  a certified extract of the resolutions of the board of directors of
          the Company referred to in Clause 3.2; and

     (d)  a certified extract of its board (and, if required, shareholders')
          resolutions approving the execution of this Agreement and such other
          documents and deeds as may be required relating to the transactions
          contemplated hereby.

3.4  At Completion, the Purchaser shall:

     (a)  pay to the Vendor the Consideration; and

     (b)  deliver or procure to be delivered to the Vendor such documents and
          deeds as may be required relating to the transactions contemplated
          hereby.

4.   VENDOR'S WARRANTIES

4.1  The Vendor hereby warrants to the Purchaser that:

     (i)  the Vendor being the legal and beneficial owner of the Sale Share is
          entitled to sell and transfer the Sale Share and pass full legal and
          beneficial ownership thereof to the Purchaser free from all claims,
          charges, liens, options, encumbrances and equities of any kind
          whatsoever;

     (ii) the Vendor has the power and authority to enter into this Agreement,
          and to perform its obligations hereunder and enter into all
          transactions contemplated by this Agreement and all necessary
          corporate and other action has been taken to authorise the execution,
          delivery and performance by it of this Agreement and the documents
          herein contemplated;

     (iii) the execution and delivery of, and the performance by the Vendor of
          its obligations under this Agreement will not result in a breach of
          any provision of the memorandum or articles of association of the
          Vendor or any Group Company;

<PAGE>

     (iv) this Agreement constitutes and when executed will constitute valid,
          legal and binding obligations on the part of the Vendor in accordance
          with its terms;

     (v)  the Sale Share represents the entire issued and allotted share capital
          of the Company and is fully paid up;

     (vi) the information contained in Schedule 1 is true and accurate.

4.2  The Vendor shall forthwith notify the Purchaser upon becoming aware of any
     event which is expected to cause any of the Vendor's warranties in Clause
     4.1 to be incorrect, misleading or breached in any material respects.

4.3  The Vendor's warranties set out in each paragraph of Clause 4.1 shall be
     separate and independent and save as expressly provided shall not be
     limited by reference to any other paragraph or anything else in this
     Agreement

5.   PURCHASER'S REPRESENTATIONS AND WARRANTIES

5.1  The Purchaser hereby represents and warrants to the Vendor that:

     (a)  the Purchaser has the power and authority to enter into this
          Agreement, and to perform its obligations hereunder and enter into all
          transactions contemplated by this Agreement and all necessary
          corporate and other action has been taken to authorise the execution,
          delivery and performance by it of this Agreement and the documents
          herein contemplated;

     (b)  the execution and performance of this Agreement and the documents
          herein contemplated do not violate any applicable law, rule or
          regulation to which the Purchaser is subject; and

     (c)  this Agreement constitutes and will constitute valid, legal and
          binding obligations on its part in accordance with its terms.

5.2  The Purchaser shall forthwith notify the Vendor upon becoming aware of any
     event which is expected to cause any of the Purchaser's warranties in
     Clause 5.1 to be incorrect, misleading or breached in any material
     respects.

5.3  The Purchaser's warranties set out in each paragraph of Clause 5.1 shall be
     separate and independent and save as expressly provided shall not be
     limited by reference to any other paragraph or anything else in this
     Agreement.

6.   FURTHER ASSURANCE

     Subject to and notwithstanding Completion, each party agrees with and
     undertakes to the other party that at any time and from time to time upon
     the written request of any other party, such party will:

<PAGE>

     (a)  promptly and duly execute and deliver any and all such further
          instruments and documents and do or procure to be done all and any
          such acts or things as the other party may reasonably deem necessary
          in obtaining the full benefits of this Agreement and of the rights and
          ownership herein granted; and

     (b)  do or procure to be done each and every act or thing which the other
          party may from time to time reasonably require to be done for the
          purpose of enforcing the other party's rights under this Agreement.

7.   CONFIDENTIALITY

7.1  Each party undertakes that it shall not reveal, and shall cause its
     shareholders, directors, senior executives, employees and agents not to
     reveal, to any third party any information concerning the transactions
     contemplated hereunder and/or the contents hereof (collectively,
     "Confidential Information") without the prior written approval of the other
     party hereto.

7.2  Nothing in this Section 7 shall prevent a party hereto from using or
     disclosing any Confidential Information which (a) is already known by such
     party at the time it is disclosed to it; (b) has been rightfully received
     by such party from a third party without a breach of an obligation of
     confidentiality; (c) is in the public domain through no wrongful act of
     such party; (d) is independently developed by such party without use,
     directly or indirectly, of the Confidential Information; (e) is required to
     be disclosed by applicable law, regulation or legal process or by judicial
     order; or (f) is released in connection with the proposed spin off and
     listing of Hutchison Telecommunications International Limited.

7.3  Notwithstanding anything contained in this Agreement, either party
     acknowledges and agrees that the other party may be required by law or any
     competent regulatory body (including but without limitation to The Stock
     Exchange of Hong Kong Limited and the Securities and Futures Commission) to
     issue time sensitive and/or urgent announcements relating to this Agreement
     or matters contemplated under this Agreement. Either party shall procure to
     be provided to the other party a copy of each drafts of such time sensitive
     and/or urgent announcements promptly, and shall consider in good faith any
     comments provided to it in a timely manner by the other party to the extent
     reasonably practicable within the time frame stipulated by law or by the
     relevant competent regulatory body.

8.   ENTIRE AGREEMENT

8.1  This Agreement together with all other documents which are referred to in
     this Agreement as being required by its terms to be entered into by the
     parties or any of them in connection with this Agreement set out and
     constitute the entire agreement and understanding between the parties
     relating to the transactions hereby contemplated and supersede any previous
     or contemporaneous drafts, representations, warranties, promises,
     assurances, arrangements, discussions, negotiations, agreements

<PAGE>

     or undertakings relating thereto whether written or oral and no party shall
     rely on any representations or warranties except those expressly stated
     herein.

8.2  No purported alteration or variation of this Agreement shall be effective
     unless it is in writing, refers specifically to this Agreement and is duly
     executed by each of the parties hereto.

9.   ASSIGNABILITY

     This Agreement shall enure for the benefit of successors of the respective
     parties hereto but shall not be assignable.

10.  NOTICES

10.1 Any notice or other communication given or to be given pursuant to this
     Agreement shall be in writing sent or delivered to the party at the address
     or facsimile number as set out below or as may be notified by such party to
     the other:-

     Vendor:-

     Address:     22nd Floor, Hutchison House, 10 Harcourt Road, Hong Kong
     Attention:   Company Secretary
     Fax no.:     (852) 2128 1778

     Purchaser:-

     Address:     22nd Floor, Hutchison House, 10 Harcourt Road, Hong Kong
     Attention:   Company Secretary
     Fax no.:     (852) 2128 1778

10.2 Any notice or other communication shall be deemed to have been received if
     sent by facsimile, on the date of transmission, or if delivered personally,
     when delivered, or if sent by post, 7 days if overseas and 48 hours if
     local after the date of posting.

10.3 Reference in Clause 10.1 to writing shall include a notice or communication
     by facsimile.

11.  COSTS AND EXPENSES

     Each party shall bear its own costs and expenses in relation to the
     negotiations leading up to the sale and purchase of the Sale Share and to
     the preparation, execution and carrying into effect of this Agreement and
     all other documents referred to in it which relate to the sale and purchase
     of the Sale Share. The Vendor confirms that no

<PAGE>

     expense of whatever nature relating to the sale and purchase of the Sale
     Share has been or is to be borne by the Company.

12.  COUNTERPARTS

12.1 This Agreement may be executed in any number of counterparts, and by the
     parties on separate counterparts, but shall not be effective until each
     party has executed at least one counterpart.

12.2 Each counterpart shall constitute an original of this Agreement, but all
     the counterparts shall together constitute but one and the same instrument.

13.  INVALIDITY

     Each provision of this Agreement is severable and distinct from the others
     and if at any time any provision of this Agreement is or becomes illegal,
     invalid or unenforceable in any respect under the law of any jurisdiction,
     that shall not affect or impair:-

     (a)  the legality, validity or enforceability in that jurisdiction of any
          other provision of this Agreement; or

     (b)  the legality, validity or enforceability under the law of any other
          jurisdiction of that or any other provision of this Agreement.

14.  GOVERNING LAW

     This Agreement shall be governed by and construed in accordance with the
     laws of Hong Kong and the Purchaser hereby submits to the exclusive
     jurisdiction of the Hong Kong courts.

<PAGE>

IN WITNESS whereof this Agreement has been duly executed on the date first above
written.

SIGNED by Ting Chan            )
for and on behalf of           )   /s/ Ting Chan
HTHK LIMITED                   )   ------------------------------
In the presence of:-           )


/s/ Steven P. Allen
----------------------------


SIGNED by Edith Shih           )
for and on behalf of           )
HUTCHISON TELECOMMUNICATIONS   )   /s/ Edith Shih
LIMITED                        )   ------------------------------
In the presence of:-           )


/s/ Patricia Hui
----------------------------

<PAGE>

                                  The Schedule

             Particulars of Hutchison Mobile Communications Limited

 1. Date of Incorporation         :   8 September 2003

 2. Place of Incorporation        :   British Virgin Islands

 3. Incorporation number          :   559134

 4. Address of Registered Office  :   P.O. Box 957, Offshore Incorporations
                                      Centre, Road Town, Tortola,
                                      British Virgin Islands

 5. Business                      :   Dormant

 6. Authorised Share Capital      :   US$50,000 divided into 50,000 shares
                                      of US$1.00 each

 7. Issued Share Capital          :   US$1

 8. Shares held as follows        :

    Registered Holder   Beneficial Owner   No. of Shares Held
    -----------------   ----------------   ------------------
    HTHK Limited        HTHK Limited               1

 9. Directors                     :   Susan Chow
                                      Craig Erlich
                                      Edmond Ho
                                      Neil McGee
                                      Robin Sng

10. Secretary                     :   NIL

11. Auditors                      :   PricewaterhouseCoopers

12. Financial Year End Date       :   31 December

13. Outstanding Mortgages/Charges :

Date   Instrument   Property Mortgaged/Charged   Amount Secured
----   ----------   --------------------------   --------------
                    NIL