Washington - Republican presidential hopeful Tom Tancredo says the best way he can think of to deter a nuclear terrorist attack on the U.S. is to threaten to retaliate by bombing Islamic holy sites.

The Colorado congressman on Tuesday told about 30 people at a town-hall meeting in Osceola, Iowa, that he believes such a terrorist attack could be imminent and that the U.S. needs to hurry up and think of a way to stop it.

U.S. Rep. Tom Tancredo, R-Colo., speaks with supporters during a campaign stop at Silver Eagle Harley-Davidson/Buell motorcycle dealership in Waterloo, Iowa, Saturday, May 12, 2007. Tancredo participated in a local annual motorcycle ride of ABATE of Iowa, a statewide motorcycle safety and awareness group. (AP | Scott Mussell, The Waterloo Courier)

"If it is up to me, we are going to explain that an attack on this homeland of that nature would be followed by an attack on the holy sites in Mecca and Medina," Tancredo said at the Family Table restaurant. "Because that's the only thing I can think of that might deter somebody from doing what they otherwise might do."

Mecca and Medina, in Saudi Arabia, are Islam's holiest cities.

A Washington-based Islamic civil rights and advocacy group responded Thursday, calling Tancredo's statement "unworthy of anyone seeking public office in the United States."

"Perhaps it's evidence of a long-shot candidate grasping at straws and trying to create some kind of a controversy that might appeal to a niche audience of anti-Muslim bigots," said Ibrahim Hooper, spokesman for the Council on American-Islamic Relations.

This isn't the first time Tancredo has suggested such action.

In 2005, he drew international criticism after he told a radio talk-show host that "you could take out" Islamic holy sites if terrorists ever launched a nuclear attack against the United States.