"The Muslims have said either we kneel or they're going to kill us," former prisoner of war in Vietnam Bud Day said on a conference call with reporters organised by the Floridan Republican party.

"I don't intend to kneel and I don't advocate to anybody that we kneel, and John doesn't advocate to anybody that we kneel."

Day was a prisoner of war at the same time as McCain, and was a member in 2004 of the "Swift Boat Veterans for Truth" group that sought to discredit then Democratic White House hopeful John Kerry's statements about his own service in the Vietnam war.

McCain campaign spokesman Michael Goldfarb sought to clarify Day's remarks on Friday after the conference call, saying: "The threat we face is from radical Islamic extremism."

However, Day's words prompted a quick reply from US-based Muslim groups. "Mr Day's distorted view dismisses the vast majority of Muslims who stand with our nation to fight extremists and anti-American forces," said Council on American-Islamic Relations legislative director Corey Saylor.