President Donald Trump has said he will not allow the US to become a “migrant camp”, as he stood by his administration’s immigration crackdown.
“The United States will not be a migrant camp,” he said at the White House. “And it will not be a refugee-holding facility – it won’t be.”
Photos over the weekend showed undocumented children being held in fenced enclosures at a Texas facility.
The UN human rights chief has condemned the policy as “unconscionable”.
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Mr Trump said on Monday: “You look at what’s happening in Europe, you look at what’s happening in other places.
We cannot allow that to happen to the United States. Not on my watch.”
Earlier, he said European countries had made a big mistake by allowing in millions of migrants.
Mr Trump criticised Chancellor Angela Merkel of Germany in particular, saying her people were turning against their leaders because of the issue.
Mrs Merkel is in a migration dispute with her interior minister, Horst Seehofer, who wants to refuse migrants if they have already registered for asylum elsewhere in the EU.
What’s the policy?
Nearly 2,000 children have been separated from their parents at the border between mid-April and the end of May.
The administration’s “zero tolerance” policy entails criminally charging those entering the US illegally, including asylum seekers.
This has led to parents being separated from their children, who are not charged with a crime.
As a result, hundreds of children are being housed in detention centres, including warehouses and converted supermarkets.
Some shelters and foster homes have said they are running out of space.
On Sunday, Father’s Day, Democratic lawmakers visited shelters and processing facilities in New Jersey and Texas, demanding to see detainees.
Officials have also announced plans to erect tent cities that will hold hundreds more children in the Texas desert where temperatures regularly reach 40C (105F).