A British court blocked the UK from transferring sovereignty over the contested  Chagos Islands  to Mauritius hours before the agreement was due to be signed.

The UK agreed to hand Mauritius the Indian Ocean archipelago, which is home to the largest of the islands, Diego Garcia, a strategically important naval and bomber base.

The agreement was due to be signed by British Prime Minister Keir Starmer and Mauritian leader Navin Ramgoolam at a virtual ceremony. However, the High Court granted an injunction following legal action brought by two British-Chagossian women born on the islands, Bernadette Dugasse and Bertrice Pompe.

The UK was under pressure from international actors to renounce the territory that was separated from Mauritius in 1965.

The agreement, delayed by political changes in Mauritius and the US, gained support after former US President Trump indicated backing despite earlier national security concerns.

British officials announced in October 2024 that they would cede sovereignty over the Chagos Archipelago to Mauritius, while keeping control of Diego Garcia, the largest island, which is home to a U.S.-UK military base.

The UK would then lease back the base for at least 99 years.