WASHINGTON -- CIA Director Michael V. Hayden said publicly for the first time yesterday that his agency had used the harsh interrogation technique known as "waterboarding" on three al-Qaida suspects, and he testified that depriving the agency of coercive methods would "increase the danger to America."

In the most detailed public comments to date on a CIA program that had been shrouded in secrecy for years, Hayden said the agency had used simulated drowning to extract critical information from terrorism suspects in 2002 and 2003.

He also testified that only three detainees were ever subjected to the method: Khalid Shaikh Mohammed, the alleged mastermind of the Sept. 11 attacks; Abu Zubaydah, an al-Qaida operative tied to the Sept. 11 plot; and Abd al-Rashim al-Nashiri, a Saudi suspected of playing a key role in the bombing of the U.S. destroyer Cole in Yemen in 2000.

Appearing before the Senate Select Committee on Intelligence, Hayden said the CIA had ceased using waterboarding nearly five years ago, but he made a vigorous case for preserving the agency's ability to use so-called "enhanced" interrogation techniques.

Information provided by two of the prisoners who underwent waterboarding - Mohammed and Zubaydah - accounted for 25 percent of the human intelligence reports circulated by the CIA on al-Qaida in the five years after the Sept. 11 attacks, Hayden said.

And at a time when Congress is considering imposing sweeping new restrictions on the CIA, Hayden warned of potentially deadly consequences.

"If you create a box, we will play inside the box without exception," he said. "My view is that would substantially increase the danger to America."

Hayden's testimony came during a hearing that was supposed to focus on national security threats. Instead, the session was dominated by a renewed debate over spy powers the Bush administration asserted after the Sept. 11 attacks, particularly interrogation methods.

Some Democrats on the panel have said that waterboarding amounts to torture. And the panel's chairman, Sen. John D. Rockefeller IV, a West Virginia Democrat, questioned whether the CIA's harsh methods "undermined our moral standing" and reduced cooperation in the war on terrorism.

But even among administration officials testifying yesterday, there were signs of shifting positions and divisions on the issue. At one point, Mike McConnell, the nation's top intelligence officer, sought to back away from recent comments in a magazine article indicating that he considered waterboarding a form of torture.

McConnell acknowledged the severity of the technique, saying that "waterboarding, taken to its extreme, could be death." Even so, he said, there are scenarios in which it might be employed. "It is a legal technique," he said, "used in a specific set of circumstances."

Moments after McConnell's comments, FBI Director Robert S. Mueller III seemed to undercut the case for using extreme methods, testifying that FBI agents had extracted critical information from high-value detainees, including former Iraqi dictator Saddam Hussein, without resorting to coercive techniques.

Asked whether the FBI's more controlled methods were effective, Mueller said, "We believe so."

The sparring came during testimony in which the nation's top intelligence officials offered a mixed assessment of the security environment confronting the United States. They contrasted security improvements in Iraq with growing violence and unrest in Pakistan. McConnell testified that 1,360 Pakistanis were killed by suicide bombings and other extremist attacks in 2007, more than in the previous six years combined.

The assassination in December of former Prime Minister Benazir Bhutto "could embolden Pashtun militants," McConnell said.

Greg Miller writes for the Los Angeles Times.