Written questions by Francois.

Commonwealth and Development Affairs, with reference to the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), if will list the measures in the Agreement that address the wrongs of the past as stated in the preamble to that Agreement; and what estimate has he made of the cost to the public purse of those measures over the next ten years.

The costs of the Treaty have been published in the Finance Exchange of Letters, laid in Parliament together with the Treaty on 22 May.

Commonwealth and Development Affairs, with reference to Article 3(3) of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), how his Department plans will co-operate with the Government of Mauritius on trafficking in narcotics; and what estimate has he made of the cost to the public purse of such co-operation over the next ten years.

The new UK-Mauritius Strategic Partnership Framework will provide a comprehensive mechanism for delivering for the UK and Mauritius, including on areas such as narco-trafficking. UK and Mauritian Ministers will meet in the coming months to finalise the partnership and will then meet in an Annual Strategic Dialogue. This will review and keep evolving the Framework as necessary to support the security and prosperity of our countries into the future.

Commonwealth and Development Affairs, with reference to Article 11 of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), what oversight the UK plans to ensure the Government of Mauritius will use the grants to (a) promote the ongoing economic development and (b) welfare of (i) Mauritius and (ii) its people.

Full details of the mechanisms of use for the development framework grant will be agreed between the UK and Mauritius during the implementation period, before the first payment of the grant in year 4 of the Agreement.

With reference to the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), what steps his Department is taking to ensure the storage of (a) fuel and (b) weapons in Diego Garcia as defined in Article 19 of the Agreement (i) comply with the environmental laws of the Government of Mauritius and (ii) maintain operational readiness.

The United Kingdom is not bound by Mauritian environmental law. Under Article 5, the UK will apply applicable international environmental law with due regard to applicable Mauritian environmental laws; this reflects the long-standing Defence policy of applying both our own and our host nations' environmental standards so far as it is reasonably practicable. Annex 1.2.ii explicitly puts the management of fuels, weapons and other hazardous materials under UK control.

Commonwealth and Development Affairs, with reference to paragraph 6(e) of Annex 1 of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), what steps his Department would be able to take under the Agreement if the Government of Mauritius breached the terms of the Agreement.

Both sides have negotiated this Agreement in good faith and we are confident that Mauritius intends to uphold it in full, just as we will. Were an issue to arise in relation to the interpretation or application of the Agreement, that would be resolved in accordance with the dispute settlement provisions in the treaty.   While any disputes were being resolved, the Agreement would remain in force and we would have the full legal basis to continue to exercise all the rights and authorities necessary for the operation of the base, as well as the legally binding protections to keep our adversaries out of the area.

Commonwealth and Development Affairs, with reference to paragraph 2 of Annex 1 of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), through what mechanism his Department will expeditiously inform the Government of Mauritius of an armed attack emanating from Naval Support Facility Diego Garcia; and what steps he will take to ensure that the disclosure of such information does not compromise operations.

Any notification will take place after the event and will not require the UK to divulge sensitive information. Agreement to inform a host nation is standard practice in many such arrangements, while the UN Charter itself has a requirement to notify the UN of military action taken in self-defence.

With reference to paragraph 5 of Annex 1 of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), what steps his Department plans to take to provide assistance to the Government of Mauritius for (a) monitoring and (b) detecting security risks in the Chagos archipelago.

Work on the details to implement the treaty is ongoing across Government, including engagement with Mauritius as appropriate. Defence’s contribution will centre on developing Mauritian capability to provide maritime security through improved maritime domain awareness and broader capability development.

What estimate he has made of the cost of the public purse of contributing to the Government of Mauritius’s maritime security including (a) training and (b) equipment over the next ten years.

As set out in the new UK-Mauritius Strategic Partnership Framework, Mauritius and the United Kingdom will cooperate on matters relating to maritime security. Further engagement on the details of this cooperation with Mauritius is ongoing. Our contribution will focus on providing training and building institutional partnerships which will contribute to preserving the safety, security, stability and prosperity of the Indian Ocean region and will support the future operation of the Base on Diego Garcia.

With reference to paragraph 3(h) of Article 2 of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), what steps he plans to take to ensure the Government of Mauritius's regulation of the provision of electronic communications services does not impact the communication systems of Naval Support Facility Diego Garcia.

The UK has unrestricted ability to control and manage the electromagnetic spectrum for Diego Garcia and the surrounding 12 nautical miles. Decisions related to the electromagnetic spectrum beyond Diego Garcia will be taken jointly by the UK and Mauritius at the Joint Commission, which is described in Annex 3 of the Treaty. There can be no decisions without UK agreement.

With reference to paragraph 1(b)(iii) of Annex 1 of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), what steps he plans to take to ensure the exclusive command and control over military personnel in Diego Garcia as defined in Article 19 of the Agreement.

The UK has full command and control over UK military personnel on Diego Garcia. There are no means for Mauritius to obtain command and control over UK military personnel as a result of the treaty.

Commonwealth and Development Affairs, with reference to Article 5(2) of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), what estimate he has made of the cost to the public purse supporting the Government of Mauritius in (a) establishing and (b) managing the Chagos Archipelago Marine Protected Area over the next ten years.

The Blue Belt Programme, which is funded by the Foreign, Commonwealth and Development office, currently supports BIOT to manage the current Marine Protected Area. As the Treaty states, the terms of the management and support provided by the UK to Mauritius to establish and manage the Chagos Archipelago Marine Protected Area will be agreed between the Parties by a separate written instrument, as part of implementation of the Agreement.

Commonwealth and Development Affairs, with reference to paragraph 8 of Annex 2 of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), if he will set out the facilities his Department will provide to support law enforcement officials of the Government of Mauritius in Diego Garcia as defined in Article 19 of the Agreement.

The UK will support the exercise of jurisdiction of Mauritius on Diego Garcia over (i) Mauritian nationals who are not members of UK armed forces or of US personnel, and (ii) all persons not connected to the operation of the Base. This ensures that Mauritius has jurisdiction over any future illegal migration to the island, closing off a dangerous immigration route to the UK.

With reference to paragraph 8(d) of Annex 2 of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), what steps his Department plans to take to provide assistance to the Government of Mauritius in the (a) arrest in and (b) transfer of prisoners from Diego Garcia as defined in Article 19 of the Agreement.

The UK will support the exercise of jurisdiction of Mauritius on Diego Garcia over (i) Mauritian nationals who are not members of UK Armed Forces or US personnel, and (ii) all persons not connected to the operation of the Base. This ensures that Mauritius has jurisdiction over any future illegal migration to the island, closing off a dangerous and costly immigration route to the UK.

With reference to the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), how he will ensure the (a) security and (b) operational continuity of Comprehensive Nuclear-Test-Ban Treaty Organisation monitoring stations on Diego Garcia under Mauritian sovereignty.

The United Kingdom shall continue to be responsible for the administration and facilitation of maintenance of the Comprehensive Nuclear-Test-Ban Treaty Organisation monitoring stations on Diego Garcia. The arrangements are described in the International Organisations exchange of letters.

With reference to Article 5(3) of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), what steps his Department is planning to take to co-operate with the Government of Mauritius on (a) illegal, (b) unreported, and (c) unregulated fishing in the Chagos Archipelago.

In conjunction with the steps taken elsewhere in Government, the Ministry of Defence will support closer collaboration between the UK and Mauritius in this area by providing training which boosts Mauritian maritime security capabilities and maritime domain awareness.

With reference to paragraph 8(b) of Annex 2 of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), what steps his Department plans to take to provide assistance to the Government of Mauritius for the carrying out of all necessary investigations into offences; and what estimate has he made of the cost to the public purse of such assistance over the next ten years.

As per paragraph 10 of Annex 2, the UK and Mauritius will be agreeing separate arrangements and operating procedures as necessary to assist and facilitate the exercise of Mauritian jurisdiction in respect to paragraph 8. There will be no additional facilities on island to enable Mauritian jurisdiction.

With reference to paragraph 5 of Annex 1 of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), what estimate he has made of the cost of providing assistance to the Government of Mauritius to (a) monitor, (b) detect, and (c) adjudicate security risks and (d) conduct security reviews over the first ten years of the Agreement.

As set out in the new UK-Mauritius Strategic Partnership Framework, Mauritius and the United Kingdom will cooperate on matters relating to maritime security. Further engagement on the details of this cooperation with Mauritius is ongoing. Securing the future operation of the Base on Diego Garcia was the objective of the treaty with Mauritius and that will remain the objective in the work to operationalise the treaty.

With reference to Article 6 of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), what steps he will take to prevent unauthorised access to Diego Garcia as defined in Article 19 of the Agreement.

Under the treaty, Mauritius will have the ability to conduct resettlement on any island in the Chagos Archipelago other than Diego Garcia. The UK has no intention of constraining resettlement activity, but has negotiated an effective veto over any activity that presents a clear and direct threat to the base on Diego Garcia. The United Kingdom controls access, and therefore authorisations, for all persons permitted to be on Diego Garcia.

With reference to paragraph 1(b)(viii) of Annex 1 of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), what security protocols his Department will establish for (a) non-United Kingdom and (b) non-United States vessels accessing Diego Garcia as defined in Article 19 of the Agreement.

This provision enables the United Kingdom to permit and control access to Diego Garcia by partner states. No further security protocols are required.

With reference to Article 5 of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), whether his Department has contingency plans to address potential restrictions on operations at Naval Support Facility Diego Garcia in the event of the Government of Mauritius citing infringements of the Mauritian environmental laws.

The United Kingdom is not bound by Mauritian environmental law. Under Article 5, the UK will apply applicable international environmental law with due regard to applicable Mauritian environmental laws; this reflects the long-standing Defence policy of applying both our own and our host nations' environmental standards so far as it is reasonably practicable.