Boris Johnson and Jeremy Hunt have joined Theresa May in condemning Donald Trump’s tweets suggesting four Democratic congresswomen should “go back and help fix” their “broken and crime-infested” countries, but all held back from branding him a racist.

The two Conservative leadership hopefuls made clear their criticism of Trump in a Sun and TalkRadio leadership debate, echoing May’s comments that they were “completely unacceptable”.

This video has been removed. This could be because it launched early, our rights have expired, there was a legal issue, or for another reason. Boris Johnson and Jeremy Hunt refuse to call Trump's comments racist – video

Asked for his views, Johnson, the runaway favourite to succeed May as prime minister next week, said: “Relations between the UK and US are incredibly important. But if you are the leader of a great multiracial, multicultural country you simply cannot use that kind of language about sending people back to where they came from. It went out decades and decades ago and thank heavens for that. It’s totally unacceptable.”

Pressed on whether he agreed with May, Hunt said: “Yes I do. I have three half-Chinese children and if anyone ever said to them, ‘Go back to China’ I would be utterly appalled. It is totally un-British to do that. So I hope that would never happen in this country.”

They were each asked whether Trump should be called a racist because of his comments but Hunt, the foreign secretary, and Johnson, a former foreign secretary, both declined to use that term.

Earlier, May took the unusual step of commenting on US domestic politics after Trump made reference to the outspoken Democratic congresswomen, only one of whom is foreign-born.

The president’s remarks were attacked as explicitly racist towards Alexandria Ocasio-Cortez, Ayanna Pressley, Rashida Tlaib and Ilhan Omar, who was born in Somalia.

The speaker of the US House of Representatives, Nancy Pelosi, denounced Trump’s “xenophobic comments meant to divide our nation”, while the four congresswomen accused him of trying to appeal to white nationalists.

Q&A What did Trump say in his racist ‘go back’ tweets? Show Hide On 14 July Trump sent a series of tweets saying: “So interesting to see ‘Progressive’ Democrat Congresswomen, who originally came from countries whose governments are a complete and total catastrophe, the worst, most corrupt and inept anywhere in the world (if they even have a functioning government at all), now loudly and viciously telling the people of the United States, the greatest and most powerful Nation on earth, how our government is to be run. Why don’t they go back and help fix the totally broken and crime infested places from which they came. Then come back and show us how it is done. These places need your help badly, you can’t leave fast enough. I’m sure that Nancy Pelosi would be very happy to quickly work out free travel arrangements!” The US president did not name his targets, but the attack was directed at congresswomen Alexandria Ocasio-Cortez of New York; Ayanna Pressley of Massachusetts; Rashida Tlaib of Michigan; and Ilhan Omar of Minnesota. Only Omar, who is from Somalia, was not born in the US. Trump has subsequently launched several further attacks on the congresswoman accusing them of "foul language & racist hatred". On 16 July he tweeted that they had been "spewing some of the most vile, hateful, and disgusting things ever said by a politician in the House or Senate, & yet they get a free pass and a big embrace from the Democrat Party. Horrible anti-Israel, anti-USA, pro-terrorist & public shouting of the F...word, among many other terrible things." He also reiterated the 'go home' message, tweeting "IF YOU ARE NOT HAPPY HERE, YOU CAN LEAVE!"

Downing Street criticised Trump’s comments but stopped short of branding him a racist. “Her view is that the language which was used to refer to the women was completely unacceptable,” the prime minister’s official spokesman said.

Trump was highly critical of May last week, saying she had made a “mess” of Brexit, following leaked diplomatic cables from the UK ambassador to Washington that described him as inept and insecure.

Johnson, who was condemned for his failure to defend the ambassador, Sir Kim Darroch, is keen to rebuild the relationship with the US after the serious diplomatic row.

Johnson has claimed he said nothing that should have been a factor in the ambassador’s decision to quit, but that is not an assessment shared in Whitehall or by Darroch.

Q&A What did Sir Kim Darroch write about Trump in the cables? Show Hide In the cables allegedly leaked to the Mail on Sunday, the UK’s outgoing ambassador to Washington, Sir Kim Darroch told his bosses in London that: He did not believe the Trump administration would “become substantially more normal; less dysfunctional; less unpredictable; less faction riven; less diplomatically clumsy and inept”.

Trump may have been indebted to “dodgy Russians”.

There were bitter divisions within the Trump White House, saying euphemistically that administration officials would get into “knife fights”.

The Trump presidency could “crash and burn” and that “we could be at the beginning of a downward spiral ... that leads to disgrace and downfall”.

The US president’s approach to global trade could wreck the system on which it depends.

Trump could attack Iran, and that he abandoned the Iran nuclear deal as an act of 'diplomatic vandalism' to spite Barack Obama.

The White House was split over the withdrawal, and lacked a "day-after" plan for what might come next.

Trump had condemned Darroch and sought to ostracise him in an attempt to punish the envoy and apparently to drive him from his job.

No 10 says Trump's 'go back home' tweet to congresswomen 'completely unacceptable' - live news Read more

The latest row about Trump’s remarks is a test case of how far the next prime minister will put what they regard as the national economic interest and the pursuit of the special relationship ahead of defending essential British values and principles.

There is a fear that with Brexit imminent, an increasingly isolated UK will have to turn more towards a Trump-led administration in its search for key allies.

May’s condemnation of Trump is a further sign the prime minister is willing to loosen the shackles in the final days of her premiership and say what she thinks.

The Scottish Conservative leader, Ruth Davidson, said earlier that May was right and “both men vying to be her successor should say so”.

Scotland’s first minister, Nicola Sturgeon, said the president’s comments were “not OK and diplomatic politeness should not stop us saying so, loudly and clearly”.

Nadhim Zahawi, the MP for Stratford-on-Avon and a supporter of Johnson, said the UK should not interject into American politics, but described the language used as inappropriate. “It is not language I would use. I am condemning it,” he told the BBC.

“It is domestic US policy. Ultimately, if we do this [interject], we will give Donald Trump the right to intervene in our politics any time he wants. That is not where we want to be. This is our greatest ally. The president of the US has to be someone with whom the prime minister can work, and if we are going to start behaving in this way and attack them all the time then they have every right to do the same back to us.”