Republican presidential front-runner Donald Trump on Monday called for a ban on Muslims entering the US in the most dramatic response by a candidate yet to last week's shooting spree by two Muslims who the FBI said had been radicalized.

"We have no choice," Trump said at a rally in South Carolina, warning of more Sept. 11-style attacks if stern measures are not taken.

Trump's statement on "preventing Muslim immigration" drew swift and fierce blowback from many directions, including the White House, rivals for the 2016 Republican presidential nomination, Democratic presidential front-runner Hillary Clinton and Republican former Vice President Dick Cheney, who said the idea "goes against everything we stand for and believe in."

"Donald Trump is unhinged. His 'policy' proposals are not serious," Republican presidential hopeful Jeb Bush said in a tweet.

"Until we are able to determine and understand this problem and the dangerous threat it poses, our country cannot be the victims of horrendous attacks by people that believe only in Jihad and have no sense of reason or respect for human life," Trump said.

Trump campaign manager Corey Lewandowski, asked in an email if the shutdown would apply specifically to immigration or more broadly to student visas, tourists and other travelers to the United States, replied: "Everyone."

Nihad Awad, national executive director of the Council on American-Islamic Relations, a Muslim advocacy group, blasted Trump.

"This is outrageous coming from someone who wants to assume the highest office in the land. It is reckless and simply un-American. Donald Trump sounds more like a leader of a lynch mob than a great nation like ours," Awad said. – Reuters