'Will suspend immigration from nations with terror history'

White House hopeful Donald Trump vowed on Monday to "suspend immigration" from nations with a "proven history" of terrorism against the US or other allies, one day after the deadly attack on a Florida nightclub.

"When I'm elected, I will suspend immigration from areas of the world where there is a proven history of terrorism against the United States, Europe or our allies, until we fully understand how to end these threats," Trump said in New Hampshire.

"We cannot continue to allow thousands upon thousands of people to pour into our country, many of whom have the same thought process as this savage killer." 

"Clinton wants to allow radical Islamic terrorists to pour into our country," he said, highlighting how such extremists have enslaved women and murdered homosexuals.

"Immigration is a privilege, and we should not let anyone in this country who doesn't support our communities."

Speaking of the Orlando shooter, who was born in New York to Afghan parents, Trump said "the only reason the killer was in America in the first place was because we allowed his family to come here."

"We have a dysfunctional immigration system which does not permit us to know who we let into our country," he added.

Trump's blunt comments come six months after he controversially called for a ban on Muslims entering the United States.

He also expressed strong support for America's gay community, following Sunday's attack on the gay nightclub in Orlando left 50 people dead including the shooter.

"This is a very dark moment in America's history," Trump said.

"It's a strike at the heart and soul of who we are as a nation," he added.

"It's an assault on the ability of free people to live their lives, love who they want and express their identity."