He continued: “They’re talking about a very long-term, powerful lease, a very strong lease, about 140 years actually.

“That’s a long time, and I think we’ll be inclined to go along with your country.”

Under the Chagos plan, the UK is expected to lease Diego Garcia for 99 years, with an option for a 40-year extension.

However, progress has been delayed to allow the new US administration to look at details of the deal.

Foreign Secretary David Lammy had suggested on ITV’s Peston programme the agreement could be off if it did not get the president’s backing “because we have a shared military and intelligence interest with the United States and of course they’ve got to be happy with the deal”.

Earlier this month, Mauritian Prime Minister Navin Ramgoolam said US representatives would be present in negotiations over the islands.

The plan to cede sovereignty of the archipelago, known officially as the British Indian Ocean Territory, was announced in October 2024 after a deal was reached with former Mauritian leader Pravind Jugnauth.

However, Jugnauth conceded defeat in a parliamentary election a month later, and Ramgoolam has criticised the deal negotiated by his predecessor.

The agreement has been mired in uncertainty after Trump’s re-election as US president, given several US Republicans have argued it could deliver a potential security boost to China.

Sir Keir has also faced questions over whether the money to pay Mauritius for leasing back the military base would come out of the increase in defence spending announced earlier this week.

Mauritius, a former British colony, has long argued it was illegally forced to give the Chagos Islands away in return for its own independence in 1968.

The UK has come under increasing international pressure to hand over control of the archipelago after various United Nations bodies, including its top court and general assembly, sided with Mauritian sovereignty claims in recent years.

The previous Conservative government opened negotiations over their legal status in late 2022, but the party has attacked the agreement struck by Labour.