LONDON -- Angelina Jolie says she is "very disheartened" by the U.S. response to the global migration crisis, and fears countries will adopt increasingly isolationist policies instead of acting together to tackle the challenge.

The special envoy for the United Nations refugee agency said Monday that worries about uncontrolled immigration has given a "false air of legitimacy to those who promote politics of fear and separation."

"It has created the risk of a race to the bottom, with countries competing to be the toughest," she said at a migration event sponsored by the BBC in London.

She said nations need to pull together to deal with the world's 60 million displaced people by rebuilding a co-ordinated and orderly system for dealing with refugees and migrants.

"I have been very, very disheartened by my own country's response to the situation," Jolie said.

She referred to Republican presidential contender Donald Trump, who suggested a temporary ban on all Muslims entering the U.S. in the wake of attacks by extremists.

"To me, America is built on people from around the world coming together for freedoms, and especially freedom of religion," she said. "And so it is hard to hear that this is coming from someone who's pressing to be an American president."