Written questions by Francois.

With reference to paragraph 6(b) 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 that the UK's submission does not compromise the Naval Support Facility Diego Garcia’s operations.

The UK is not obligated under the treaty to provide any operationally sensitive detail to Mauritius. Any submissions made under Annex 1 paragraph 6 will undergo assessment by the UK in consultation with the US to ensure operations are not compromised.

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 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 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 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(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 Article 3 of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), how his Department will co-operate with the Government of Mauritius on maritime security, including efforts to combat (a) trafficking and (b) piracy.

Mauritius and the United Kingdom will cooperate on matters relating to maritime security. Our contribution will focus on providing training and building institutional partnerships. This 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 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 Article 10 of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), what steps will his Department take to determine compliance with the appropriate level of security clearance for Mauritian nationals (a) seeking and (b) during employment on Diego Garcia as defined in Article 19 of the Agreement.

There are robust security measures in place on Diego Garcia for all employees, contractors and suppliers. These standards will continue to be upheld following entry into force of the treaty.

With reference to paragraph 1(a) of Annex 1 of the document entitled UK/Mauritius: Agreement concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), whether the Agreement permits (a) access, (b) basing, and (c) overflight rights for (i) United Kingdom and (ii) United States forces in the (i) territory, (ii) waters and (iii) airspace of the Government of Mauritius outside of Diego Garcia as defined in Article 19 of the Agreement.

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.

With reference to paragraph 8(a) of Annex 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 of providing assistance to the Government of Mauritius in the provision of (a) facilities and (b) amenities for Mauritian law enforcement officials on Diego Garcia as defined in Article 19 of the Agreement 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 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.