Sir Keir Starmer has refused to say whether he would sign away other British overseas territories after handing the Chagos Islands to Mauritius.
The archipelago was British-owned from 1814 but was signed away by the Government in a deal that it claimed would safeguard global security by ending a long-running dispute.
The islands include Diego Garcia, which hosts a strategically important US-UK military base.
The Prime Minister was asked to guarantee that under Labour no other British overseas territories will be signed away.
He told reporters in response: “The single most important thing was ensuring that we had a secure base, the joint US-UK base; hugely important to the US, hugely important to us.
“We’ve now secured that and that is why you saw such warm words from the US yesterday.”
A spokesman for No10 told GB News: “Chagos does not change our policy or approach to other overseas territories.”
His remarks came just hours after Argentina pledged to gain “full sovereignty” of the Falkland Islands in the wake of the Chagos deal.
The country’s foreign minister, Diana Mondino, welcomed the step taken by Sir Keir’s Government on Thursday towards ending “outdated practices”.
She pledged “concrete action” to ensure that the Falklands – the British territory that Argentina calls the Malvinas and claims as its own – are ceded to Buenos Aires.
Grant Shapps, the former Tory defence secretary, told The Telegraph: “The decision by Starmer to give up the British Indian Overseas Territory proves he cannot be trusted to protect British interests.
“We are lucky that Starmer wasn’t in charge when Argentina invaded the Falklands, he would have handed them over on a silver platter.”
Sir Keir has been criticsed by a number of Conservative figures for the decision, including by Boris Johnson, who claimed that the decision was out of “sheer political correctness”.
The former prime minister told Camilla Tominey on GB News: “What is this claim? It’s nonsense, it’s total nonsense. Why are we doing this? Sheer political correctness, desire to look like the good guys, a desire to look as though we are unbundling the last relics of our empire. It’s nonsense.”
Meanwhile, Nigel Farage demanded that there be a vote in Parliament on the decision, saying that no Government “should be able to surrender sovereignty without debate”.
