The prime minister has said that discussions are ongoing with the United States over a controversial deal to hand the Chagos Islands to Mauritius, amid concerns the US could withdraw support for the agreement.
Under the deal, which the US backed last year, the UK would transfer sovereignty of the islands to Mauritius and lease back a joint UK-US military base on the largest island, Diego Garcia.
Ministers insist the deal is necessary to protect the base from "malign interests", but last week President Trump called it "an act of great stupidity".
The Conservatives have accused the government of undermining national security because of Mauritius's close ties to China.
Speaking to reporters while travelling to Beijing, Sir Keir Starmer said he had discussed it with Donald Trump "a number of times" and said the issue had been "raised with the White House at the tail end of last week, over the weekend and into the early part of this week".
