• Mr Trump said the women "originally came from countries whose governments are a complete and total catastrophe".
• He was referring to four congresswomen - three who were born in the US and one who came as a child refugee.
British Prime Minister Theresa May has criticised US President Donald Trump for calling on several Democratic congresswomen of colour to "go home".
The outgoing PM called Mr Trump's words "completely unacceptable", according to her spokesperson.
Mr Trump said the women "originally came from countries whose governments are a complete and total catastrophe".
He was referring to four congresswomen - three who were born in the US and one who came as a child refugee.
His remarks were widely condemned as racist, and as having gone beyond previous statements and actions by the president that drew allegations of racism.
Prospective Democratic presidential candidates denounced Mr Trump's tweets as racist and divisive. Republican Party representatives kept quiet
The women - Alexandria Ocasio-Cortez, Rashida Tlaib and Ayanna Pressley, and Ilhan Omar, who came to the US as a refugee aged 12 - all called the president racist and were been backed by members of the Democratic Party.
Ms Ocasio-Cortez was born in the Bronx in New York, approximately 12 miles away from the Queens hospital where Mr Trump was born.
Mrs May resigned as UK prime minister in June after being unable to get a Brexit deal through parliament. Two candidates in the governing Conservative Party are currently vying to replace her.
What did the president say?
In a three-tweet thread, Mr Trump accused the congresswomen of "viciously" criticising him and the US.
The president did not explicitly name the women he was talking about, but the context - and references to House Speaker Nancy Pelosi - made a clear link. He said Ms Pelosi would happily organise for them to leave the country.
A week ago, Ms Pelosi clashed with the four women - sometimes nicknamed "the squad" - but she has since come to their defence following his tweets.
When I call the president a racist, this is what I'm talking about
— Bernie Sanders (@BernieSanders) July 14, 2019
We must stand together for justice and dignity towards all. https://t.co/lweeJk7NoF
The president wrote: "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!"
There have been internal feuds among Democrats over a border funding package, with Ms Pelosi arguing in favour of the package, and the four women - all newcomers to Congress with a progressive agenda - voting against.
Last week, Ms Ocasio-Cortez accused Ms Pelosi of singling out women of colour for criticism.