His critics described the methods as torture and said they sullied America's reputation around the world.

"The bill Congress sent me would take away one of the most valuable tools in the war on terror," Bush said in his weekly radio address taped for broadcast yesterday. "So today I vetoed it."

The bill provides guidelines for intelligence activities for the year and includes the interrogation requirement. It passed the House in December and the Senate last month.

"This is no time for Congress to abandon practices that have a proven track record of keeping America safe," the president said.

Sen. Dianne Feinstein (D., Calif.), a member of the Senate Intelligence Committee, said Bush ignored the advice of 43 retired generals and admirals and 18 national security experts, including former secretaries of state and national security advisers, who supported the bill.

"This president had the chance to end the torture debate for good, yet he chose instead to leave the door open to use torture in the future," Feinstein said. "Torture is a black mark against the United States."

House Speaker Nancy Pelosi said Congress would work to override Bush's veto next week. "In the final analysis, our ability to lead the world will depend not only on our military might, but on our moral authority," said Pelosi (D., Calif.).

But based on the margin of passage in each chamber, it would be difficult for the Democratic-controlled Congress to turn back the veto. It takes a two-thirds majority, and the House vote was 222-199 and the Senate's was 51-45.

Senate Majority Leader Harry Reid (D., Nev.) said Bush often warns against ignoring the advice of U.S. commanders on the ground in Iraq. Yet the president has rejected the Army Field Manual, which recognizes that harsh interrogation tactics elicit unreliable information, Reid said.

Jennifer Daskal, senior counterterrorism counsel at Human Rights Watch, said Bush would "go down in history as the torture president" for defying Congress and allowing the CIA to use interrogation techniques "that any reasonable observer would call torture."

"The Bush administration continues to insist that CIA and other nonmilitary interrogators are not bound by the military rules and has reportedly given CIA interrogators the green light to use a range of so-called 'enhanced' interrogation techniques, including prolonged sleep deprivation, painful stress positions, and exposure to extreme cold," Daskal said. "Although waterboarding is not currently approved for use by the CIA, Attorney General Michael B. Mukasey has refused to take it off the table for the future."

The intelligence bill would limit CIA interrogators to the 19 techniques allowed for use by military questioners. The Army Field Manual in 2006 banned using methods such as waterboarding or sensory deprivation on uncooperative prisoners.

Bush said the CIA must retain use of "specialized interrogation procedures" that the military does not need. The military methods are designed for questioning "lawful combatants captured on the battlefield," while intelligence professionals are dealing with "hardened terrorists" who have been trained to resist the techniques in the Army manual, the president said.

"We created alternative procedures to question the most dangerous al-Qaeda operatives, particularly those who might have knowledge of attacks planned on our homeland," Bush said. "If we were to shut down this program and restrict the CIA to methods in the field manual, we could lose vital information from senior al-Qaeda terrorists, and that could cost American lives."

Bush said the program had helped stop plots against a Marine camp in Djibouti and the U.S. consulate in Karachi, Pakistan, and plans to fly passenger planes into a Los Angeles tower or London's Heathrow Airport and city buildings.

"Were it not for this program, our intelligence community believes that al-Qaeda and its allies would have succeeded in launching another attack against the American homeland," the president said.

Sen. John D. Rockefeller 4th (D., W.Va.), chairman of the Senate Intelligence Committee, said he had heard nothing to suggest that the CIA, through enhanced interrogation methods, had obtained information to thwart a terrorist attack. "On the other hand, I do know that coercive interrogations can lead detainees to provide false information in order to make the interrogation stop," Rockefeller said.

The CIA director said in a memo yesterday to agency employees that it is not a choice between a "blanket application of the Army Field Manual or the legalization of torture."

The manual "does not exhaust the universe of lawful interrogation techniques," Mike Hayden wrote. "There are methods in CIA's program that have been briefed to our oversight committees, [that] are fully consistent with the Geneva Convention and current U.S. law, and are most certainly not torture."

He said military and intelligence missions are different. Hayden described the CIA program as a "tightly controlled and carefully administered national option that goes beyond the Army Field Manual" and has been a "lawful and effective response" to the threat of terrorism. "It will continue to be so as we work within the boundaries established by our nation's laws," he wrote.

The 19 interrogation techniques allowed by the Army Field Manual include the "good cop/bad cop" routine; making prisoners think they are in another country's custody; and separating a prisoner from others for up to 30 days.

Among the techniques the manual prohibits are:

Hooding prisoners or putting duct tape across their eyes.

Stripping prisoners naked.

Forcing prisoners to perform or mimic sexual acts.

Beating, burning or physically hurting them in other ways.

Subjecting prisoners to hypothermia or mock executions.

It does not allow food, water and medical treatment to be withheld. Dogs may not be used in any aspect of interrogation.

But waterboarding is the most high-profile and contentious method in question.

It involves strapping a person down and pouring water over his cloth-covered face to create the sensation of drowning. It has been traced back hundreds of years to the Spanish Inquisition and is condemned by nations around the world and human-rights organizations as torture.

The Detainee Treatment Act of 2005 includes a provision barring cruel, inhuman and degrading treatment for all detainees, including CIA prisoners, in U.S. custody. Many people believe that covers waterboarding.

There are concerns that the use of waterboarding would undermine the U.S. human-rights efforts overseas and could place Americans at greater risk of being tortured when captured.

The military specifically prohibited waterboarding in 2006. The CIA also prohibited the practice in 2006 and says it has not been used since 2003.

Still, waterboarding remains in the CIA's tool kit. The technique can be used, but it requires the consent of the attorney general and president on a case-by-case basis. Bush wants to keep that option open.

The administration has refused to rule definitively on whether it is torture. Bush has said many times that his administration does not torture.