Donald Trump has appeared to compare Keir Starmer to Neville Chamberlain in his latest disparaging remarks about the prime minister, who has refused to back the US-Israeli attacks on Iran.

The comments, during an Easter Monday event at the White House, underline Trump’s continued annoyance at Starmer’s scepticism about the aims and legality of the conflict, a view that has not been shifted by the US president’s jibes.

In somewhat unclear comments, Trump told reporters that the UK had “a long way to go”, adding: “We won’t want another Neville Chamberlain, do we agree? We don’t want Neville Chamberlain.”

Chamberlain is most commonly used by today’s politicians as a warning against not standing up to tyrannical regimes, because of his discredited pre-second world war policy of trying to appease Hitler’s Germany.

Trump, whose rhetoric has become increasingly erratic during the course of the Iran conflict, now in its sixth week, has ditched his once cordial approach to Starmer in favour of repeatedly mocking the prime minister.

During an Easter lunch speech at the White House, footage of which emerged on Friday, Trump claimed Starmer had said he would have to “ask my team” about sending UK aircraft carriers to support the conflict, impersonating Starmer in a demeaning way.

UK officials said the US never requested the vessels and the UK had not offered them. In the wake of the latest comments by Trump, government sources pointed to Starmer’s previous comments, including at a press conference last week, about always prioritising the UK’s national interests.

UK aircrews and ground forces have undertaken defensive action in the Middle East, with the Ministry of Defence saying RAF gunners shot down “multiple” Iranian drones overnight on Sunday.

Starmer has not directly responded to Trump’s insults and mockery, beyond saying he would stick to his position of not involving the UK in offensive operations “whatever the pressure and the noise”.

Other world leaders have been more direct. After Trump talked about the idea of pulling the US out of Nato last week, the French president, Emmanuel Macron, responded with open annoyance, saying: “You have to be serious. When you want to be serious, you don’t go around saying the opposite every day of what you just said the day before. And perhaps you shouldn’t talk every day.”

Trump told Iran in an expletive-filled social media post on Easter Sunday to open up the strait of Hormuz, a key international shipping passage, to all vessels, saying that if this did not happen by Tuesday the US would target civilian infrastructure in Iran, a probable war crime.

Asked about the comments on Monday, Bridget Phillipson, the UK education secretary, said: “It is not language or an approach that this government would be taking.”

She added: “Our approach as a UK government, the approach that the prime minister, Keir Starmer, has set out, is that we are not getting involved in offensive action, we won’t be getting involved in offensive action.”