UK Prime Minister Keir Starmer Thursday signed a deal transferring sovereignty of the Chagos Islands to Mauritius, including the key Diego Garcia military base.
The base, which plays a central role in UK-US defence operations in the Indian Ocean, will now be leased from Mauritius under a new 99-year lease.
Speaking in Hertfordshire, Starmer said a “full assessment” of the reasons behind the deal was “highly classified,” but indicated the UK faced a likely legal defeat at international courts had it not reached a settlement. He noted such a defeat could have come with punitive damages.
Under the deal, the UK will pay Mauritius an average of £101 million ($129m) per year — amounting to a total of £3.4 billion ($4.35 billion) over the course of the lease. Starmer also claimed the arrangement would cost less than operating an aircraft carrier annually.
The US, which co-operates the Diego Garcia base with the UK, will shoulder the base’s operational costs — which Starmer said exceed the UK’s financial contribution. Former US President Donald Trump has publicly welcomed the deal.
Earlier, in the day, a London High Court judge issued a last-minute injunction to the deal—only to later lift it, clearing the way for the agreement to proceed.
According to Reuters, the initial injunction was granted in the early hours of Thursday in response to a legal challenge filed by Bernadette Dugasse and Bertrice Pompe, British nationals born on Diego Garcia. The two argued that the Chagossian community had been sidelined in the negotiations and not consulted on a deal that directly affects their ancestral homeland.
The High Court had been scheduled to review the case at 10:30 am local time. However, in a later hearing, Justice Chamberlain ruled: “I have concluded that the stay granted by Justice Goose should be discharged and there should be no further interim relief. The agreement can be concluded today and it does not necessarily have to be at 9:00.”
Responding to the court’s decision, James Eadie, representing the Foreign, Commonwealth and Development Office, said: “My instructions from Number 10 are that we need a decision by 1pm today if we are to sign today, and everybody is standing by.”
As per the Reuters report, many members of the wider Chagossian diaspora, most of whom were forcibly removed from the islands over 50 years ago and now live in the UK, have also said they cannot endorse any agreement made without their input.
Critics have warned the deal could be a strategic mistake, suggesting it hands diplomatic leverage to China, which maintains strong trade ties with Mauritius.
British Prime Minister Keir Starmer had been expected to take part in a virtual signing ceremony with Mauritian officials, according to The Telegraph.
While as per Reuters, the UK government declined to comment on the ongoing legal proceedings, it defended the deal, saying it was “the right thing to protect the British people and the country’s national security.”
Britain detached the Chagos Islands from Mauritius in 1965—three years before Mauritius gained independence—and formed the British Indian Ocean Territory.
Under the proposed terms, Britain would pay Mauritius £3 billion ($4 billion) over the 99-year lease period. The agreement includes a potential 50-year extension and a clause giving the UK right of first refusal thereafter.
Diego Garcia, the largest island in the archipelago, has played a pivotal role in military operations, including US-UK strikes on Houthi targets in Yemen (2024–2025), humanitarian missions to Gaza, and earlier, bombing campaigns against the Taliban and al-Qaeda in Afghanistan in 2001.
US President Donald Trump voiced his support for the deal in February following a meeting with Starmer in Washington. His predecessor, Joe Biden, had also backed the agreement.
