Ashcroft testified before the House Judiciary Committee, CNN reported. The committee is holding hearings on whether the Bush administration permitted torture to be used on suspected terrorists.
"I believe a report of waterboarding would be serious, but I do not believe it would define torture," Ashcroft said.
Ashcroft said that as far as he knows U.S. agents used waterboarding three times on suspects who "would be labeled as high-value detainees." He said he had heard from former CIA Director George Tenet that "enhanced interrogation techniques" had yielded valuable information.
Earlier this year, President Bush vetoed a bill that would have outlawed some interrogation techniques, including waterboarding or simulated drowning. The bill would have limited the CIA to techniques allowed in the Army Field Manual.