WASHINGTON — President Bush yesterday defended the CIA's harsh interrogation of terrorism suspects, saying its methods do not constitute torture and are necessary to protect America from attack.

But Bush's declaration that the United States "does not torture people" did little to dampen the fallout from fresh evidence that his administration has used secret legal memos to sanction tactics that stretch, if not circumvent, the law.

The president's comments came amid disclosures this week of classified opinions issued by the Justice Department in 2005 that endorsed the legality of an array of tough interrogation tactics, ranging from sleep deprivation to simulated drowning.

Bush's decision to comment again on what once was among the most highly classified U.S. intelligence programs underscores the political peril surrounding the issue for the White House, which has had to retreat from earlier, aggressive assertions of executive power.

It also reflects the extent to which the debate over tactics in the war on terror remains unresolved, six years after the attacks of Sept. 11, 2001. The limits on CIA interrogators have been particularly fluid, shifting repeatedly under a succession of legal opinions, court rulings and executive orders.

In a brief appearance at the White House, Bush stressed the legality of the CIA program — even while making the case for continued use of coercive methods.

"We stick to U.S. law and our international obligations," Bush said. But when the United States locates a terrorism suspect, he added: "You bet we're going to detain them, and you bet we're going to question them — because the American people expect us to find out information, actionable intelligence so we can help protect them. That's our job."

The president's comments were met with outrage from key Democrats in Congress.

"The administration can't have it both ways. I'm tired of these games," said Sen. John D. Rockefeller IV of West Virginia, chairman of the Senate Intelligence Committee. "They can't say that Congress has been fully briefed while refusing to turn over key documents used to justify the legality of the program."

The issue is expected to confront Michael B. Mukasey, Bush's nominee to be the next attorney general, at a Senate confirmation hearing later this month.

The two memos that surfaced publicly this week are among a collection of documents the White House has refused to turn over to congressional committees examining the CIA detention and interrogation program.

The newly uncovered memos, which were described for the first time Thursday by The New York Times, were drafted by the Justice Department shortly after Alberto Gonzales took over as attorney general in February 2005. They appear to show that the Bush administration was continuing to condone harsh interrogation techniques by the CIA even as Congress was moving to outlaw them.

One of the memos, written by the department's Office of Legal Counsel, authorized the CIA to use a combination of painful interrogation tactics, including head-slapping, extreme temperatures and simulated drowning, known as water-boarding.

A later opinion declared that none of the controversial methods violated a congressional ban on "cruel, inhuman and degrading" treatment of prisoners that lawmakers enacted in late 2005.

The secret memos were issued at a time when the administration appeared to be signaling publicly that it was backing off from the most aggressive forms of coercive interrogation.

In December 2004, the Justice Department published an analysis by the Office of Legal Counsel that declared torture to be "abhorrent," and rejected an earlier opinion finding that methods short of causing "organ failure, impairment of bodily function or even death" were legally permissible.

The memos since have been superseded by an executive order Bush issued in July, establishing stricter limits on CIA interrogation methods and requiring the agency to comply with the Geneva Convention on treatment of prisoners.

The order bans "torture, cruel or inhuman treatment, mutilation or maiming" as well as sexual humiliation or the denigration of religious objects or beliefs. But it contains loopholes that appear to allow certain coercive methods to continue.

One provision lists the "basic necessities of life" that are to be provided any prisoner, including adequate food, water and shelter. But the section makes no mention of sleep, and experts said the order appears to permit the use of stress positions as well as rough physical treatment.

A companion document spelling out in more detail the techniques that the CIA is allowed to employ remains classified and has not been released to the public.

The White House yesterday reiterated its long-standing refusal to discuss individual techniques, saying their disclosure would benefit U.S. foes.

Some lawmakers and military officials have expressed concern that the Bush administration has established a confusing system in which the CIA is free to go far beyond strict interrogation limits adopted by the military in September 2006 in the aftermath of the Abu Ghraib prison scandal.

Some also worry that in sanctioning harsh methods, the United States is inviting other countries to employ similar techniques on captured U.S. personnel.