LONDON (REUTERS) - Both candidates vying to replace Theresa May as Britain's prime minister said they agreed with her that the language used by US President Donald Trump about a group of mostly American-born Democratic congresswomen was unacceptable.

Mr Trump on Sunday (July 14) told the group to "go back and help fix the totally broken and crime infested places from which they came", a comment that was condemned by Democrats as racist.

Asked during a leadership debate whether they agreed with Mrs May that the comments were unacceptable, both frontrunner Boris Johnson and foreign minister Jeremy Hunt said they did.

"Relations between the UK and the US are incredibly important but if you are the leader of great multi-racial, multi-cultural society you simply cannot use that kind of language about sending people back to where they came from," Mr Johnson said.

"So it is totally unacceptable."

Asked whether the comments were racist, both Mr Johnson and Mr Hunt declined to use that term however.

"This is the president of the country which happens to be our closest ally and so I think it is not going to help the situation to use that kind of language about the president of the United States," Mr Hunt said.

"But I have made absolutely clear how totally offensive it is to me that people are still saying that kind of thing."

Democrats in the US Congress moved on Monday to formally condemn Mr Trump's attacks on the congresswomen as House of Representatives Speaker Nancy Pelosi said her party would introduce a resolution criticising his "xenophobic tweets".

All four of the congresswomen Mr Trump appeared to reference - representatives Alexandria Ocasio-Cortez, Ilhan Omar, Ayanna Pressley and Rashida Tlaib - are US citizens. Three were born in the United States while Omar, a Somali refugee, arrived in 1992.