Arizona Sen. John McCain on Thursday leapt at the opportunity to criticize GOP presidential frontrunner Rudy Giuliani over the torture issue, after the former New York mayor said he might allow some uses of waterboarding and said he was unsure of the interrogation technique's definition.

"All I can say is that it was used in the Spanish Inquisition, it was used in Pol Pot's genocide in Cambodia, and there are reports that it is being used against Buddhist monks today,” McCain told The New York Times in an interview.

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McCain, who is vying for the GOP nomination, said his fellow presidential candidates: "They should know what it (waterboarding) is. It is not a complicated procedure. It is torture.”

At a town hall meeting Thursday in the early caucus state of Iowa, Giuliani told a questioner that waterboarding — an interrogation technique in which suspects are made to feel like they are drowning — should not be done, but he added a number of caveats.

"It depends on how it is done. It depends on the circumstances. It depends on who does it," he said.

"I think the way it has been defined in the media, it shouldn’t be done. ... I would say if that is the description of it, then I can agree that it shouldn’t be done," Giuliani said, adding that he doesn’t necessarily trust the media's description and has yet to learn "what the real description of it is."