London. Britain signed an agreement Thursday handing sovereignty over the contested and strategically located Chagos Islands to Mauritius, a move the government says ensures the future of a US-UK military base that is vital to British security.

The Indian Ocean archipelago is home to a strategically important naval and bomber base on the largest of the islands, Diego Garcia.

Under the agreement, the UK will pay Mauritius 101 million pounds ($136 million) per year to lease back the base for at least 99 years.

UK Prime Minister Keir Starmer said that the base, operated by US forces, is crucial for British counterterrorism and intelligence and is “right at the foundation of our safety and security at home.”

The signing was delayed for several hours after a UK judge imposed a last-minute injunction blocking the transfer. That was later lifted by another judge.

High Court judge Martin Chamberlain said after a hearing on Thursday that an injunction barring the handover should be removed. He said “the public interest and the interests of the United Kingdom would be substantially prejudiced” if there was a further delay.

The agreement was due to be signed by Starmer and Mauritian leader Navin Ramgoolam at a virtual ceremony on Thursday morning.

But a judge granted an injunction in the early hours of Thursday, blocking the British government from taking any “conclusive or legally binding step” to hand the islands to a foreign government.

The injunction came in response to a claim by two Chagossian women representing the islands' original residents, who were evicted decades ago to make way for the American base. Bernadette Dugasse and Bertrice Pompe, both British citizens, fear it will become even harder to return to their birthplace once Mauritius takes control of the islands.

After the injunction was lifted, Pompe said it was "a very sad day,“ but vowed to continue fighting.

“We do not want to hand over our rights to Mauritius. We are not Mauritians,” she said outside the High Court.

“The rights we are asking for now, we have been fighting for for 60 years," she added. "Mauritius is not going to give that to us.”

One of the last remnants of the British Empire, the Chagos Islands have been under British control since 1814. Britain split the islands away from Mauritius, a former British colony, in 1965, three years before Mauritius gained independence.

Britain evicted as many as 2,000 people from the islands in the 1960s and 1970s so the US military could build the Diego Garcia base, which has supported US military operations from Vietnam to Iraq and Afghanistan.

Displaced Chagossians fought unsuccessfully in UK courts for years for the right to go home. Under the deal, a resettlement fund would be created to help displaced islanders move back to the islands, apart from Diego Garcia. Details of any such measures remain unclear.

Mauritius has long contested Britain’s claim to the archipelago, and in recent years the United Nations and its top court have urged Britain to return the Chagos to Mauritius, around 2,100 kilometers (1,250 miles) southwest of the islands.

In a non-binding 2019 opinion, the International Court of Justice ruled that the UK had unlawfully carved up Mauritius when it agreed to end colonial rule in the late 1960s.

The British government says those rulings put the future of the Diego Garcia base, vital to UK security, at stake. Negotiations on handing the islands to Mauritius began in 2022 under the previous Conservative government and resumed after Starmer's Labour Party was elected in July.

A draft agreement was struck in October, but was delayed by a change of government in Mauritius and reported quarrels over how much the UK should pay to lease the base.

The UK also paused to consult the US after the change of government in Washington. President Donald Trump’s administration gave its approval.

The UK’s opposition Conservatives have criticized the deal, accusing the government of surrendering sovereignty over a British territory.

“We should not be paying to surrender British territory to Mauritius," Conservative leader Kemi Badenoch said.