Question to the Foreign, Commonwealth & Development Office:

To ask the Secretary of State for Foreign, Commonwealth and Development Affairs, with reference to Article 19 and Annexes 5 and 6 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 with the Government of Mauritius to determine the precise maritime zones of (a) the Chagos Archipelago and (b) Diego Garcia.

The UN Convention on the Law of the Sea (UNCLOS) sets out the international legal basis on which States can establish coastal baselines and maritime zones, including a territorial sea and exclusive economic zone. Once the Treaty enters into force, the determination or delimitation of any maritime zones around the Chagos Archipelago will be a matter for Mauritius, in accordance with UNCLOS. The UK will have rights, as set out in the Treaty in relation to a 12 nautical mile zone surrounding the island of Diego Garcia, and in relation to the zone between 12 and 24 nautical miles surrounding the island of Diego Garcia.