New York, Apr 20 : C. I. A. officers used the waterboarding, the near-drowning technique, against 9/11 planner Khalid Shaikh Mohammed 183 times, according to a 2005 Justice Department legal memorandum.

A CIA memo quoting Inspector General, says that intelligence officers used the waterboard at least 83 times during August 2002 against Abu Zubaydah.

The release of the numbers is likely to become part of the debate about the morality and efficacy of interrogation methods that the Bush Administration Justice Department declared legal even though the US had historically treated them as torture.

A former CIA officer, John Kiriakou, had told ABC News and other news media organizations in 2007 that the first prisoner questioned in the CIA's secret overseas detention program in 2002, Abu Zubaydah, had undergone waterboarding for only 35 second before agreeing to tell everything he knew.

The New York Times reported in 2007 that Mohammed had been barraged with more than 100 different harsh interrogation methods, causing CIA officers to worry that they might have crossed legal limits and halting his questioning.

The Senate Intelligence Committee has begun a yearlong investigation of the CIA interrogation program, in part to assess claims of Bush Administration officials that brutal treatment, including slamming prisoners into walls, shackling them in standing positions for days and confining them in small boxes, were necessary to get information.

The fact that waterboarding was repeated so many times may raise questions about its effectiveness, as well as assertions by Bush Administration officials that their methods were used under strict guidelines.

A footnote to another 2005 Justice Department memo released on Thursday said waterboarding was used both more frequently and with a greater volume of water than the CIA rules permitted.

The sentences in the 2005 memo including the number of times the two men were waterboarded appear to be redacted from some copies of the memo but visible in others. (ANI)