C.I.A. interrogators used waterboarding, the near-drowning technique that top Obama administration officials have described as illegal torture, 266 times on two key prisoners from Al Qaeda, far more than had been previously reported.
The C.I.A. officers used waterboarding at least 83 times in August 2002 against Abu Zubaydah, according to a 2005 Justice Department legal memorandum. Abu Zubaydah has been described as a Qaeda operative.
A former C.I.A. officer, John Kiriakou, told ABC News and other news media organizations in 2007 that Abu Zubaydah had undergone waterboarding for only 35 seconds before agreeing to tell everything he knew.
The 2005 memo also says that the C.I.A. used waterboarding 183 times in March 2003 against Khalid Shaikh Mohammed, the self-described planner of the Sept. 11, 2001, terrorist attacks.
The New York Times reported in 2007 that Mr. Mohammed had been barraged more than 100 times with harsh interrogation methods (torture), causing C.I.A. officers to worry that they might have crossed legal limits and to halt his questioning. But the precise number and the exact nature of the interrogation method was not previously known.