Theresa May has condemned Donald Trump's attack on female Democrat congressmen, saying the US president's remarks were "completely unacceptable".
Mr Trump prompted fury after suggesting the unnamed politicians should "go back" to the "broken and crime infested places from which they came".
He did not name who he was referring to, but the attack was widely interpreted as being aimed at Alexandria Ocasio-Cortez, Ilhan Omar, Rashida Tlaib and Ayanna Pressley, who have all been critical of Mr Trump's immigration policies.
Asked about Ms May's views on the comments, her official spokesman said: "The prime minister's view is that the language used to refer to these women was completely unacceptable."
The comments mark Ms May's strongest criticism of the Republican on domestic matters. She previously condemned his comments in the wake of the Charlottesville protests, but has never before used such frank language.
Mr Trump posted on Twitter: "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!"