Theresa May has said that tweets by Donald Trump calling for four Democrat congresswomen to fix the “crime infested places from which they came” are "completely unacceptable".
A Downing Street spokesperson said: “The Prime Minister’s view is that the language that was used to refer to those women was completely unacceptable.”
Donald Trump said the women were “loudly and viciously” telling the US how to run its government.
“Why don’t they go back and help fix the totally broken and crime infested places from which they came," he wrote.
"Then come back and show us how it is done. These places need your help badly, you can’t leave fast enough."
US-born Alexandria Ocasio-Cortez, who was one of those targeted, said Mr Trump was “angry” because he can’t “conceive of an America that includes us”.
The other women were US-born Ayanna Pressley and Rashida Tlaib, while Ilhan Omar was born in Somalia - all are US citizens.
(L-R) Alexandria Ocasio-Cortez, Rashida Tlaib and Ayanna Pressley
Democrat Beto O’Rourke called the comments “racist”, while Elizabeth Warren said it was a “racist and xenophobic attack”.
US house speaker Nancy Pelosi said Mr Trump wanted to “make America white again”.
Mr Trump responded: "So sad to see the Democrats sticking up for people who speak so badly of our country."
“Their disgusting language and the many terrible things they say about the United States must not be allowed to go unchallenged,” he wrote.
“If the Democrat Party wants to continue to condone such disgraceful behaviour, then we look even more forward to seeing you at the ballot box in 2020!”