Britain is giving up sovereignty of a remote group of islands in return for securing the long-term future of a strategically important military base.
The UK Government said it has reached a political agreement with Mauritius over the Chagos Islands, also known as the British Indian Ocean Territory, following negotiations which began in 2022.
Mauritius will assume sovereignty over the Indian Ocean archipelago while the joint US-UK military base remains on Diego Garcia, the largest of the islands.
The Foreign Office said the agreement means the status of the base will be undisputed and legally secure.
US President Joe Biden welcomed the “historic” agreement and said it secures the “effective operation of the joint facility on Diego Garcia into the next century”.
But Conservative leadership candidates reacted angrily, with former foreign secretary James Cleverly labelling the Government “weak” and Robert Jenrick saying there had been a “surrender”.
Chagossians were forced to leave the central Indian Ocean territory by 1973 to make way for the military base.
The expulsions are regarded as one of the most shameful parts of Britain’s modern colonial history and Chagossians have spent decades fighting to return to the islands.
The United Nations’ highest court, the International Court of Justice, previously ruled the UK’s administration of the territory was “unlawful” and must end.
Foreign secretary David Lammy said: “This Government inherited a situation where the long-term, secure operation of the Diego Garcia military base was under threat, with contested sovereignty and ongoing legal challenges.
“Today’s agreement secures this vital military base for the future.
“It will strengthen our role in safeguarding global security, shut down any possibility of the Indian Ocean being used as a dangerous illegal migration route to the UK, as well as guaranteeing our long-term relationship with Mauritius, a close Commonwealth partner.”
The Foreign Office said the agreement is subject to a treaty and supporting legal instruments being finalised, adding that both sides have committed to complete this as quickly as possible.
A Downing Street spokesman said Prime Minister Sir Keir Starmer spoke to his Mauritius counterpart, Pravind Jugnauth, on Thursday morning.
The spokesman said: “The leaders began by welcoming the political agreement achieved today between the UK and Mauritius on the exercise of sovereignty over the Chagos archipelago after two years of negotiations.
“The Prime Minister reiterated the importance of reaching this deal to protect the continued operation of the UK/US military base on Diego Garcia.
“He underscored his steadfast duty to national and global security which underpinned the political agreement reached today.”
Conservative former minister Jenrick said: “It’s taken three months for Starmer to surrender Britain’s strategic interests.
“This is a dangerous capitulation that will hand our territory to an ally of Beijing.”
Cleverly wrote on social media: “Weak, weak, weak! Labour lied to get into office. Said they’d be whiter than white, said they wouldn’t put up taxes, said they’d stand up to the EU, said that they be patriotic. All lies!”
Fellow Tory leadership candidate Tom Tugendhat said: “This is a shameful retreat undermining our security and leaving our allies exposed.”
He said the Foreign Office had “negotiated against Britain’s interest” and it was “disgraceful that these negotiations started under our watch”.
Andrew Rosindell, the Conservative MP for Romford, wrote on social media platform X: “This is a shameful betrayal by Labour.
“The right of self-determination of the Chagossian people has been disregarded. No territory of the Crown should be handed away without consent.
“The loyal people of all UK’s Overseas Territories will shudder at this announcement.”
Follow STV News on WhatsApp
Scan the QR code on your mobile device for all the latest news from around the country