Written questions by Francois.

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.

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 8(e) 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 assist the Government of Mauritius prevent unlicensed commercial fishing in Diego Garcia as defined in Article 19 of the Agreement.

In conjunction with the steps taken elsewhere in Government, the Ministry of Defence will assess the capability of Mauritius to secure its Exclusive Economic Zone and will provide targeted support, including through training, to strengthen efforts to counter illegal, unregulated and unreported fishing and support a secure and prosperous Indian Ocean region.

With reference to Article 15 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 arbitration procedures under paragraph 4.

The procedures concerning paragraph 4 of Article 15 are set out in Annex 4.

With reference to paragraph 3(b) of Annex 1 of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), what procedures his Department plans to use to notify the Government of Mauritius of the (a) maintenance and (b) upgrade of equipment in the Chagos Archipelago beyond Diego Garcia as defined in Article 19 of the Agreement.

The Joint Commission, as set out in Annex 3(6)a of the treaty, has the remit of serving as a forum for dialogue between the Parties, including the exchange of information regarding the security and protection of, and activities within, the Chagos Archipelago.

With reference to Article 3(2)(c) 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 maintain the (a) defence and (b) security of Diego Garcia as defined in Article 19 of the Agreement; and how his Department will coordinate this with the Government of Mauritius.

The objective of the treaty and the substantive obligation on both parties is the long-term, secure and effective operation of the base on Diego Garcia. Therefore, the treaty itself is designed to secure and protect the base and every obligation in the treaty is read in light of this obligation. This includes the fact that the UK has responsibility for the defence and security on Diego Garcia. Implementation measures, including the Strategic Partnership Framework, are being constructed against this treaty premise; Ministry of Defence relations with the Government of Mauritius will be supported in country by establishing a new non-Resident Defence Adviser position.

With reference to paragraph 2 of Annex 2 of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), what discussions he has had with his United States counterpart on potential agreements on the jurisdiction of US personnel in Diego Garcia as defined by Article 19 of the Agreement.

With reference to paragraph 2 of Annex 2 of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), the jurisdiction of US personnel on Diego Garcia is set out in the UK-US Exchange of Notes (EoN).

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), what steps his Department plans to take to provide assistance to the Government of Mauritius to help prevent unlicensed commercial fishing around Diego Garcia as defined in Article 19 of the Agreement; and what estimate has he made of the cost to the public purse of such assistance over the next ten years.

In conjunction with the steps taken elsewhere in Government, the Ministry of Defence will assess the capability of Mauritius to secure its Exclusive Economic Zone and will provide targeted support, including through training, to strengthen efforts to counter illegal, unregulated and unreported fishing and support a secure and prosperous Indian Ocean region.

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 notification protocols his Department will establish for (a) non-United Kingdom and (b) non-United States aircraft accessing Diego Garcia as defined in Article 19 of the Agreement.

Aircraft accessing Diego Garcia will maintain standard notification practices for flight information regions, which exist in the Indian Ocean flight information zone and other international flight information zones.

With reference to paragraph 1(v) of Annex 1 of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), whether the (a) installation and (b) repair of communication systems in Diego Garcia as defined by Article 19 of the Agreement are subject to oversight by the Government of Mauritius.

Paragraph 1(b)(v) of Annex 1 of the treaty is clear that the UK has unrestricted ability to authorise the installation, operation and repair of new and existing communication systems and electronic systems and associated cables.

With reference to paragraph 3(a) 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 ensure United Kingdom vessels have unrestricted undersea access in the Chagos Archipelago beyond Diego Garcia as defined in paragraph 11(b) of Annex 1.

In respect of the Chagos Archipelago beyond Diego Garcia, vessels and aircraft of the United Kingdom and the United States of America shall have unrestricted rights of overflight, navigation and undersea access, as at present.

With reference to paragraph 2 of Article 10 of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), how will his Department provide reasons; and what safeguards he is putting in place to ensure compliance with applicable laws.

Future contracts falling under Article 10 of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025) shall be subject to normal scrutiny and award processes. The provision of reasons to the Government of Mauritius for the non-award of a contract shall be on diplomatic channels.

With reference to paragraph 7 of Annex 1 of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), what mechanism his Department will use to notify the Government of Mauritius of ongoing activities in the Chagos Archipelago as defined in paragraph 11(b) of the Agreement that risk conflicting with the long-term, secure and effective operation of Naval Support Facility Diego Garcia.

A Joint Commission will oversee the implementation of the treaty and will discuss issues relating to the effective operation of the base on Diego Garcia.

With reference to Article 9(1) of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), how he will exercise (a) prescriptive and (b) adjudicative jurisdiction over Diego Garcia as defined in Article 19 of the Agreement to ensure operational continuity.

The prescriptive enforcement and adjudicative jurisdiction afforded to the United Kingdom under the agreement enables the UK to write, enforce, and adjudicate laws applicable on Diego Garcia. The detail of His Majesty’s Government's approach will be set out in implementing legislation.

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 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.

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.