WASHINGTON (CNN) -- Sen. Carl Levin, chairman of the Senate Armed Services Committee, says former Vice President Dick Cheney's claims -- that classified CIA memos show enhanced interrogation techniques like waterboarding worked -- are wrong.

Former VP Dick Cheney has been a vocal defender of Bush-era interrogation techniques.

Levin, speaking at the Foreign Policy Association's annual dinner in New York on Wednesday, said an investigation by his committee into detainee abuse charges over the use of the techniques -- now deemed torture by the Obama administration -- "gives the lie to Mr. Cheney's claims."

The Michigan Democrat told the crowd that the two CIA documents that Cheney wants released "say nothing about numbers of lives saved, nor do the documents connect acquisition of valuable intelligence to the use of abusive techniques."

"I hope that the documents are declassified, so that people can judge for themselves what is fact, and what is fiction," he added.

Justice Department documents released in April showed that Bush administration lawyers authorized the use of techniques such as sleep deprivation, slapping, stress positions and waterboarding, which produces the sensation of drowning.

President Obama formally banned the techniques by issuing an executive order requiring that the U.S. Army field manual be used as the guide for terror interrogations. Watch Obama discuss the torture debate »

"I can stand here tonight and say without exception or equivocation that the United States of America does not torture," he told a joint session of Congress in February.

Cheney, who has become a vocal public defender of the Bush administration's controversial interrogation policies, had asked the Obama administration to declassify the documents so there can be a more "honest debate" on the Bush administration's decision to use them on suspected terrorists.

He argued that those techniques provided valuable intelligence that saved American lives, but critics say they amounted to the illegal torture of prisoners in U.S. custody

On May 14, the CIA rejected the former vice president's request.

CIA spokesman Paul Gimigliano, in a written statement, said the two documents Cheney requested are the subject of two pending lawsuits seeking the release of documents related to the interrogation program, and cannot be declassified.

A former State Department official has told CNN that the main purpose of the Bush-era interrogations was finding a link between Iraq and al Qaeda.

Lawrence Wilkerson, chief of staff for then-Secretary of State Colin Powell, said that the interrogation program began in April and May of 2002, and Cheney's office kept close tabs on the questioning.

"Its principal priority for intelligence was not aimed at preempting another terrorist attack on the U.S. but discovering a smoking gun linking Iraq and al Qaeda," Wilkerson wrote in The Washington Note, an online political journal.

Wilkerson, a retired Army colonel, said his accusation is based on information from current and former officials. He said he has been "relentlessly digging" since 2004, when Powell asked him to look into the scandal surrounding the treatment of prisoners at Iraq's Abu Ghraib prison.

Speaking before the American Enterprise Institute, a conservative think tank, on May 21, Cheney said only detainees of the "highest intelligence value" were subjected to enhanced interrogation techniques. He said only three detainees were waterboarded.

Bush administration lawyers have said the interrogation tactics did not violate U.S. laws against torture as long as interrogators had no intent to cause "severe pain."

With thousands of lives potentially in the balance, Cheney argued, it didn't make sense to let high-value detainees "answer questions in their own good time."

Obama, speaking on the same day as Cheney, said his administration is trying to clean up "a mess" left behind by the Bush administration. He defended his plan to close the Guantanamo Bay detention center in Cuba, his ban on torture, the release of Bush-era interrogation memos and his objection to the release of prisoner photos.

Levin backed up Obama's "mess" claims, and said the enhanced interrogations have hurt America's image.

"Cheney's world view, which so dominated the Bush years and dishonored our nation, gained a little traction last week -- enough to persuade me to address it head-on here tonight," Levin said. "I do so because if the abusive interrogation techniques that he champions, the face of which were the pictures of abuse at Abu Ghraib, if they are once more seen as representative of America, our security will be severely set back."

On Thursday night, former President George W. Bush, who has remained virtually mum on the torture debate, said his administration's enhanced interrogation program was legal and garnered valuable information that prevented terrorist attacks.

Bush told an audience in Benton Harbor, Michigan, that after the September 11 attacks, "I vowed to take whatever steps that were necessary to protect you."

In his speech, Bush did not specifically refer to Obama's decision to halt the use of harsh interrogation techniques; he also didn't mention Cheney by name.

Bush described how he proceeded after the capture of terrorism suspect Khalid Sheikh Mohammed in March 2003.

"The first thing you do is ask, 'What's legal?' " Bush said. " 'What do the lawyers say is possible?' I made the decision, within the law, to get information, so I can say to myself, 'I've done what it takes to do my duty to protect the American people.' I can tell you that the information we got saved lives."

The latest charge by Levin comes as another top Democrat -- House Speaker Nancy Pelosi -- continues to defend claims that the CIA never briefed Congress on the specific interrogation methods, such as waterboarding, that were being used.

Pelosi told reporters in May that she was briefed by the CIA on such techniques once -- in September 2002, when she was the ranking Democrat on the Republican-led House Intelligence Committee -- and that she was told at the time that techniques such as waterboarding were not being used. She said she learned that waterboarding had been used after other lawmakers were briefed in 2003.

CIA spokesman George Little, however, said the agency's records indicate Pelosi was briefed on the techniques.

The claim by Pelosi, D-California, created a firestorm on Capitol Hill, with Republicans -- who have been mostly supportive of the Bush administration's policy -- blasting Pelosi and demanding she back up the allegation.

Pelosi has urged the CIA to release information on the meetings, though the CIA admits that no detailed memos, only outlines, exist.

Until concrete evidence comes to light, the torture debate will continue to heat up the halls of Congress, with Republicans putting pressure on Pelosi, and Democrats, like Levin, continuing to lash out at the former Bush administration.

CNN's Peter Hamby and Matt Smith contributed to this report.

All About Carl Levin • Dick Cheney • Torture • Barack Obama