WASHINGTON, Feb 5: The CIA on three occasions shortly after the Sept-11 attacks used a widely condemned interrogation technique known as waterboarding, CIA Director Michael Hayden told Congress on Tuesday.

‘Waterboarding has been used on only three detainees,” Hayden told the Senate Intelligence Committee. It was the first time a US official publicly specified the number of people subjected to waterboarding and named them.

Critics call waterboarding a form of illegal torture.

Congress is considering banning the technique.

Those subjected to waterboarding were suspected Sept-11 mastermind Khalid Sheikh Mohammed and senior Al Qaeda leaders Abu Zubaydah and Abd al-Rahim al-Nashiri, Hayden said.

He said waterboarding has not been used in five years but was used then because of concerns of imminent catastrophic attacks on the United States and because authorities had limited knowledge of Al Qaeda.

“The circumstances are different than they were in late 2001, early 2002,” Hayden said.

He told reporters later that the interrogations of Mohammed and Zubaydah were particularly fruitful.

From the time of their capture in 2002 until they were delivered to Guantanamo Bay prison in 2006, the two suspects accounted for one-fourth of the human intelligence reports on Al Qaeda, Hayden said.

Although some analysts have questioned Sheikh Mohammed’s credibility under interrogation, most of the information was reliable and helped lead to other Al Qaeda suspects, he said.

He told the committee he opposed limiting the CIA to using interrogation techniques permitted in the US Army Field Manual, which bans waterboarding. CIA interrogators are better trained, and it works with a narrower range of suspects in its interrogations, he said.

Hayden said fewer than 100 people had been held in the CIA’s terrorism detention and interrogation programme, with fewer than one-third of them subjected to any harsh interrogation techniques.

A senior intelligence official said after the hearing that it was unclear whether the CIA could legally use waterboarding in the future, given changes in US law. The Bush administration says it neither uses nor condones torture.

The CIA said in December that it had destroyed videotapes depicting the interrogations of Zubaydah and Nashiri, prompting a Justice Department investigation.