The U.S. attorney general says he will not investigate whether the Central Intelligence Agency broke the law when it used the interrogation technique known as waterboarding, that simulates drowning.

Speaking before the House Judiciary Committee Thursday, Michael Mukasey said the Justice Department could not investigate or prosecute people for actions that had been authorized.

Two Democratic Senators, Patrick Leahy and Sheldon Whitehouse sent a letter to Mukasey Thursday urging him to clarify testimony to a Senate committee last week, in which he said an investigation could include illegal conduct shown on videotapes of interrogations that were later destroyed by the CIA.

In other news, CIA Director Michael Hayden Thursday told the House Intelligence Committee that waterboarding is not currently used by the agency and the legality of the technique is not certain under current law.

The White House Wednesday defended the use of waterboarding on terror suspects.

On Tuesday, Hayden told U.S. lawmakers the United States used the waterboarding technique on three suspected al-Qaida detainees captured after the September 11th, 2001, terror attacks in the United States.

He said one of the detainees it was used on, Khalid Sheikh Mohammed, is one of the confessed architects of the September 11 attacks. He said the method has not be used in almost five years.

Some information for this report was provided by AFP and AP.