The top US commander in Iraq has scrapped a roster of controversial interrogation techniques, previously approved for use in Iraq, after a top Pentagon official admitted they were "not humane," defence officials said.

The order, issued by Lieutenant General Ricardo Sanchez on Thursday, coincided with a surprise trip to the Iraqi capital by US Defence Secretary Donald Rumsfeld, who visited the notorious prison in an effort to quell the growing storm over prisoner abuse there.

"On May 13, General Sanchez modified the policy," said a senior military official.

"The May 13 policy took out certain techniques - I'm sorry, certain approaches, which were not being used in any event."

The move follows an outcry in the US Congress over an interrogation policy approved for Iraqi detainees late last year which some legal experts said paid scant regard to the Geneva Convention.

The classified guidelines that surfaced at congressional hearings this past week allowed US military intelligence to seek permission to use "dietary manipulation", or food denial, place detainees in "stress positions" for up to 45 minutes and deny them sleep for up to three days in a row.

Prior approval

It also made it possible to threaten inmates with military dogs and resort to so-called "sensory deprivation," a euphemism for placing hoods over their heads for up to 72 hours.

All these methods, however, were subject to prior approval by Lieutenant General Sanchez, who, according to defence officials, has never actually sanctioned their use.

But human rights activists and legal experts say the mere existence of these guidelines may have encouraged the more serious abuses documented in a series of recently publicized pictures.

"By ratcheting up the detainees pain and discomfort, stress and duress techniques almost invariably lead to far more serious mistreatment," said Kenneth Roth, executive director of Human Rights Watch.

"Their use clearly contributed to an environment in which some US military personnel believed even more shocking abuse would be tolerated."

In his congressional testimony on Thursday, Deputy Defence Secretary Paul Wolfowitz admitted the interrogation techniques were "not humane."

Under the new policy, the "stress and duress" techniques are no longer an option, said one of the senior officials.

"What is said is simply we will not even entertain a request, so don't even send it up for a review," the official said.