Downing Street has confirmed that the UK government will not sign a deal to return the Chagos Islands to Mauritius until Donald Trump's government has had a chance to consider the future of the joint military base.

The US president-elect's allies have been critical of the deal because of its impact on the strategically important Diego Garcia base and concerns it could bolster Chinese interests in the Indian Ocean.

Ministers had been hoping to reach an agreement with Mauritius on the future of the islands before Trump is sworn in next Monday.

However, when asked about reports that the Mauritian government was seeking further talks, Keir Starmer's official spokesman said: "We will only agree a deal that is in the best interests of the UK and protects our national security. It is now clear that It is correct that the new U.S. government will have the opportunity to consider this issue and discuss it after taking office... It is completely reasonable for the new U.S. government to have the opportunity to consider the details.”

After the Mauritian government reportedly hosted a special cabinet meeting to discuss the latest proposals, the spokesman dismissed suggestions that Trump would have "veto power" over the deal. The Mauritian government was seeking further concessions and did not sign the deal, instead sending a delegation back to London for more negotiations.

Britain plans to hand over its last African colony to Mauritius while leasing back the Diego Garcia base used by the United States, at a reported cost of £90 million per year for 99 years. The British government argued that an ICJ ruling in favor of Mauritius' sovereignty meant a treaty addressing the future of the islands was the only way to guarantee the base's continued operation.

The Labor government reached an agreement with Mauritius, but a change of government in Mauritius and the election of Trump in the United States hampered progress. Discussions about the deal first began under the Conservatives.

Marco Rubio, Trump's pick for secretary of state, and incoming national security adviser Mike Walz are both critical of the plan and are believed to be watching the issue closely. Joe Biden, however, expressed support.

Starmer defended the deal during a clash with Conservative leader Kemie Badenock in the House of Commons. "We inherit a situation where the long-term operations of an important military base are threatened by legal challenges," he said.

"Negotiations began under the previous government. The then Foreign Secretary came to the house and explained why he had started negotiations and what he wanted to achieve. The aim, he said, was to "ensure the continued effective operation of the base". That’s what this deal delivers.”

Badenock said the Prime Minister was "negotiating a secret deal to hand over British territory and the taxpayers of this country will pay for this humiliation".

Asked whether the party launching the talks was "part of the problem", Badenoch's spokesman later said: "It wasn't the mistake of starting the talks, it was the current state of the talks. She knows when to walk away from a bad deal "And clearly the deal that Labor is currently negotiating is a bad deal, which is why the previous government started negotiating but the current deal is not fit for purpose."