Keir Starmer has hit out at Donald Trump over the US president’s threats to Iran suggesting he was prepared to wipe out “a whole civilisation” in the Middle East war.

The UK prime minister questioned Mr Trump’s values at a delicate time in the war with questions over whether the fragile ceasefire will hold and ahead of a state visit to the US by King Charles later this month.

Speaking to ITV’s Robert Peston, Sir Keir said: “Let me be really clear about this- they are not words I would use, ever use, because I come at this with our British values and principles.”

He added: “It is very important that I’m clear that for the United Kingdom, we have our principles, we have our values. We will be guided by them in everything that we do. That’s why I’ve said, and obviously it’s caused a degree of criticism and pressure in the last few weeks.”

The US president has previously spoken proudly of his British connections through his Scottish mother, and his own love for the royal family, so the prime minister’s criticism appeared to be a carefully chosen diplomatic way of attacking Mr Trump.

With King Charles and Queen Camilla set to be in the White House at the end of April, Mr Trump will be hoping to celebrate the occasion and his own links to British values.

But it comes at a time where the US president has repeatedly attacked Sir Keir for failing to take part in the war against Iran along with the US and Israel.

He has said the prime minister is “no Churchill” and likened him to an appeaser Neville Chamberlain.

Sir Keir also called on the Iranians to reopen the Strait of Hormuz which is still closed to international shipping but also demanded that Israel stops bombing Lebanon, an act which appears to be putting the ceasefire at risk.

In a message to Israel, he said: “That shouldn’t be happening. That should stop. That’s my strong view. And therefore the question isn’t a technical one of whether it’s a breach of the agreement or not.

“The one is actually a matter of principles as far as I’m concerned. And in a sense my argument would be it should be included in the ceasefire, and that’s the important part, the overall approach.”

But he also admitted that he along with other allies are not clear about the details of the ceasefire deal between Iran and the US, after Mr Trump withheld details following his claims that NATO has let him down over its failure to get involved in reopening the straits.

“We haven’t all got access to all the details of the ceasefire,” the PM said.

Sir Keir has been in the Middle East on a two-day trip meeting allies in the Gulf States and visiting British military personnel involved in collective defensive actions in the region against attacks from Iran.

Sir Keir told ITV’s Talking Politics podcast: “There’s a relief that there is a ceasefire, I think a sense from them that it’s fragile, that there’s a lot of work to do on the ceasefire, and so, there is a sense of relief.

“I think that’s probably shared, or my sense, shared across the United Kingdom, where people have been very concerned of what they’ve seen on their television screens, very worried about the impact it might have on them.”

The prime minister said he had discussed defence capabilities with the leaders he had met in the region.

He added: “The final emotion, if you like, is that they were pleased to see a friend, because these are longstanding allies that we have in the Gulf region – very important at a time like this for us to be here, to show that we stand with our allies.

“We’ve obviously been involved in quite intense collective self-defence with our service personnel here over the last six to seven weeks, and the expression was basically one of, it’s good to have a friend here that we can discuss these issues with at a time like this.”