WASHINGTON - Releasing classified memos showing whether harsh Bush-era interrogation methods yielded useful information from terrorism suspects is not necessary, Republican Senator John McCain said on Sunday in a public disagreement with former Vice President Dick Cheney.

After President Barack Obama released four memos this month revealing the Bush administration's legal justification for methods such as waterboarding -- a form of simulated drowning -- Cheney called for declassifying any memos showing that these techniques succeeded in producing valuable information.

No, I don't think it's necessary, to be honest with you, McCain told the CBS program Face the Nation.

Many experts say harsh interrogations lead to unreliable information because a person will say anything to stop them.

But the New York Times reported last week that Dennis Blair, Obama's national intelligence director, told colleagues in a private memo that the harsh Bush-era techniques yielded high-value information that provided a deeper understanding of the al Qaeda organization.

McCain, the 2008 Republican presidential candidate, also opposed prosecuting officials who worked on interrogation policy in former President George W. Bush's administration.

We need a united nation, not a divided one, McCain said.

Are you going to prosecute people for giving bad legal advice? ... Maybe there's an element of settling old political scores here, added McCain, who was tortured during more than five years as a prisoner during the Vietnam War.

'A NATION OF LAWS'

White House senior adviser Valerie Jarrett reiterated that Obama is letting Attorney General Eric Holder decide on moving ahead with any prosecutions.

I think the president has been very clear, and what he said is, 'We need to be a nation of laws, we need to be consistent,' and he leaves it to the attorney general to figure out who should be prosecuted for what, Jarrett told CNN.

Senator Patrick Leahy, chairman of the Senate Judiciary Committee, said a special commission is needed to get to the bottom of the Bush-era interrogation policies.

It is not from some idea of vengeance in doing this. But we know that there were a number of people that made the decision to violate the law, a number of people who said that we don't have to follow our Constitution, others who wrote memos basically saying the president and the vice president are above the law, Leahy said on the CBS show.

Speaking on NBC's Meet the Press program, White House spokesman Robert Gibbs said Obama opposes such a commission, saying the Senate intelligence committee's ongoing inquiry is the proper place for such fact finding.

Senator Dianne Feinstein, who heads the intelligence panel, told CNN on Sunday the investigation will take six to eight months.

McCain cited President Gerald Ford's decision in 1974 to give his predecessor Richard Nixon a full pardon to any crimes to move the nation past the Watergate corruption scandal that prompted Nixon to resign. Most people in retrospect believe that Ford's pardon was right, because we moved on. We have got to move on, McCain said.

McCain also said the Bush administration officials responsible for authorizing harsh interrogation methods in the aftermath of the September 11, 2001 attacks have been held accountable in the court of public opinion.

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