US president Donald Trump has launched a blistering attack on Britain, calling Sir Keir Starmer’s plan to cede the Chagos Islands to Mauritius one of “great stupidity”.

Writing on his Truth Social platform, the US president said the deal is “another in a very long line of National Security reasons why Greenland has to be acquired”.

The criticism comes just one day after the UK prime minister called for calm amongst the US and Nato allies, amid rising tensions over Trump’s Greenland ambitions.

Lashing out in an online rant, the US president wrote: “Shockingly, our “brilliant” NATO Ally, the United Kingdom, is currently planning to give away the Island of Diego Garcia, the site of a vital U.S. Military Base, to Mauritius, and to do so FOR NO REASON WHATSOEVER.”

Trump appeared to indicate his support for the deal last year, as he told Sir Keir during his visit to the White House in February that he was “inclined to go with your country” and that he had “a feeling it’s going to work out very well”.