Senior US Senator John McCain on Monday rebuked Republican presidential candidates who came out in favor of a harshinterrogation tactic known as waterboarding, bluntly calling it "torture."

"Very disappointed by statements at SC (South Carolina) GOP (Republican) debate supporting waterboarding. Waterboarding is torture," McCain said on his official Twitter feed.

Several of the party's White House hopefuls said Saturday at a debate on foreign policy that they would reverse President Barack Obama's ban on techniques that meet international definitions of torture.

They notably backed "waterboarding," a kind of controlled drowning that McCain, a former prisoner of war during the Vietnam conflict, branded as torture when he was the party's presidential nominee in 2008.

"I don't see it as torture. I see it as an enhanced interrogation technique," said former pizza restaurant chain executive Herman Cain, using a term popular under Republican former president George W. Bush.

"This is war. That's what happens in war. And I am for using the techniques -- not torture, but using those techniques that we know will extract the information to save young American lives. And I will be for it until I die," said Texas Governor Rick Perry.

"I would be willing to use waterboarding," said Representative Michele Bachmann, who sits on the House Intelligence Committee. "My strategy will be that the United States will be victorious in the war on terror."

"We have to use enhanced interrogation techniques, all enhanced interrogation techniques," agreed former senator Rick Santorum.

Leading candidate Mitt Romney was not directly asked about techniques like waterboarding, andRepresentative Ron Paul and former US envoy to China Jon Huntsman broke sharply with their rivals by denouncing the practice as torture.

"Waterboarding is torture," said Paul. "It's illegal under international law and under our law. It's also immoral and it's also very impractical. There's no evidence that you really get reliable evidence."

"We diminish our standing in the world and the values that we project, which include liberty, democracy, human rights, and open markets, when we torture," said Huntsman.

Obama weighed in on Sunday, bluntly telling the Republican candidates who support waterboarding that they were "wrong" in vowing to restore the technique.

"Waterboarding is torture," the president said. "It's contrary to America's traditions. It's contrary to our ideals."