US President Donald Trump has reportedly described UK Prime Minister Keir Starmer as “a loser” during a private dinner with friends, according to a report by The Telegraph on Wednesday.

A source quoted by the newspaper said the comment was made within the past two weeks and reflected Trump’s view that Starmer “has no future anymore.”

The remark marks a sharp shift in tone from the US president’s previous description of the prime minister as a "winner" and comes amid signs of growing tension between Washington and London.

Earlier this week, Trump publicly criticized Starmer over his response to the conflict involving Iran.

Speaking at a press conference at the White House, the US president said the British leader was “not Winston Churchill” and accused him of damaging international relationships.

Trump also criticized the UK government’s immigration and energy policies, describing them as "horrible," and urged Britain to remove what he called “sharia courts” and expand oil and gas drilling in the North Sea.

The disagreement has also centered on the use of British military facilities.

According to The Telegraph, Trump said he was “very disappointed” that the UK initially refused permission for the United States to conduct strikes from RAF bases. The British government had cited international law in its decision.

Starmer responded to Donald Trump's claim that he is "ruining" UK-US relations.

"American planes are operating out of British bases. That is the special relationship in action... British jets are shooting down drones and missiles to protect American lives in the Middle East on our joint basis... sharing intelligence every day is the special relationship in action. Hanging on to President Trump's latest words is not the special relationship in action," he said. (AA)