The UK has signed an agreement  to cede control of the disputed Chagos Islands to Mauritius, with Westminster stating that the deal safeguards the future of a US-UK military base deemed essential to British security.

The Chagos Islands, an archipelago in the Indian Ocean, include the larger island of Diego Garcia, which hosts a major naval and air base operated by the United States.

Under the agreement, the UK will pay Mauritius €120 million annually to lease the base back for a minimum 99 years.

Prime Minister Keir Starmer said the base lies at the very heart of the UK’s homeland security and defence and is crucial to the fight against terrorism and intelligence-gathering operations.

Critics argue that relinquishing the islands, which have been British territory for over 200 years, could pave the way for interference by nations such as Russia or China. The agreement has also drawn criticism from former islanders who were displaced decades ago to make way for the military installation.

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The deal was scheduled to be signed by Starmer and the Prime Minister of Mauritius, Naveen Ramgoolam, during a virtual ceremony on Thursday morning. However, it was delayed when a judge granted a last-minute injunction sought by two women of Chagossian origin. The injunction was subsequently lifted by another judge.

The agreement includes a trust fund to support Chagossian residents and permits Mauritius to organise resettlement on the islands — with the exception of Diego Garcia — though it does not guarantee it.

The Chagos Islands have been under British control since 1814. In 1965, the UK separated them from Mauritius, which gained independence in 1968.

In the 1960s and 70s, Britain forcibly removed approximately 2,000 islanders to allow the United States to establish the base on Diego Garcia. The facility has supported US military operations from Vietnam to Iraq and Afghanistan and hosts infrastructure for nuclear submarines and intelligence services.

Mauritius has long contested British sovereignty over the islands. In 2019, the International Court of Justice ruled that the UK had unlawfully detached the Chagos Archipelago from Mauritius during the decolonisation process.

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