Hillary Clinton has called Donald Trump's words about Muslims "dangerous" and "demagogic", warning that terrorist groups are using his anti-Muslim language to recruit fighters.
At the second presidential debate, Ms Clinton railed against the Republican's proposition to force Muslims to carry out "religious tests" to determine whether they adopt "American values".
"It is important for us not to say, as Donald Trump has said, that we are going to ban people based on religion," she said.
"How do you do that?
"We are a country founded on religious freedom and liberty. How are we going to do that without casuing great distress in our country?"
She added that his words were "extremely unwise".
Mr Trump replied that Ms Clinton was going to allow in 65,000 regfugees from Syria - a 550 per cent increase over president Obama - and that Americans "know nothing about their values or their love for our country".
He refused to directly answer whether he would still insist upon banning Muslims from entering the US.
"It's called extreme vetting," he said. "We are going to areas like Syria where they are coming in by the tens of thousnands because of Barack Obama and Hillary Clinton want to allow a 550 per cent increase over Obama.
"We have no idea who they are, where they are from and what their feelings are about this country."
Mr Trump called for a complete and temproary ban against Muslims in December 2015, shortly after the terrorist attacks in Paris.Reuse content