US President Donald Trump has signed an executive order to temporarily suspend the approval of some green cards.
The measure, which contains a number of exemptions, is to last for 60 days and then could be extended, he said.
Mr Trump says the order is designed to protect American workers’ jobs in an economy pummelled by the coronavirus.
Critics have accused him of using the pandemic as cover to ram through long-sought hardline immigration policies in an election year.
“This will ensure that unemployed Americans of all backgrounds will be first in line for jobs as our economy reopens,” Mr Trump said during Wednesday’s coronavirus briefing at the White House.