Congress hearing comes as ex-interrogator defends waterboarding of al-Qaeda suspect.
The manual provides 19 approved interrogation methods, and prohibits eight including waterboarding.
The White House argued that the new measure would prevent the US from conducting “lawful interrogations of senior al-Qaeda terrorists”.
The move, part of a sweeping intelligence bill, comes amid a congressional probe into the recent disclosure that the CIA destroyed videotapes of al-Qaeda suspects undergoing simulated drowning.
Variations include pouring water over face covered with cloth or cellophane, or dunking headfirst into water
Induces reflexive choking, gagging and feelings of suffocation
Dates back to the Spanish Inquisition and was used in Central and South America 30 years ago
The US president has denied the torture of suspect but refuses to disclose the approved interrogation methods employed by the Central Intelligence Agency.
Steny Hoyer, the House Democratic Leader, said the Bush administration had blurred the line “between legitimate, sanctioned interrogation tactics and torture”.
“There is no doubt our international reputation has suffered and been stained as a result.”
Backers of harsh interrogation say such methods are needed to pry vital information out of enemy combatants but critics decry torture as inhumane saying information obtained in this way is often unreliable.
Meanwhile, the US military has released two Sudanese men from Guantanamo Bay prison after nearly five years.
Adel Hassan Hamad, an aid worker, said the condition of fellow Sudanese inmate Sami al Hajj, who worked for Al Jazeera, was “very bad indeed”.