The commander of U.S. forces in Iraq has barred military interrogators from using the most coercive techniques potentially available to them in the past, declaring that requests to employ the measures against detainees will no longer even be considered, officials said yesterday.

The directive from Lt. Gen. Ricardo Sanchez comes in the face of a political uproar over disclosure earlier this week that U.S. interrogators had been allowed to request permission from Sanchez to use a range of tough interrogation tactics on a case-by-case basis.

Since October, officials said, Sanchez has approved 25 such requests, all involving prolonged isolation of detainees, the officials said. But interrogators were free under the previous policy to seek authorization for other, more severe measures, including sleep deprivation, diet manipulation, stress positions and the use of dogs to threaten detainees.

Three requests to place detainees in stressful positions to get them to talk were submitted but denied at the brigade level, the officials said without disclosing the reasons for the rejections.

At a Pentagon briefing, the officials repeated arguments that such intensified interrogation measures were entirely consistent with the Geneva Conventions requiring humane treatment of detainees. But that judgment was vigorously challenged this week by lawmakers, human rights experts and others after the Senate Armed Services Committee released an Army document that had been posted on the wall of the Abu Ghraib prison listing nine high-pressure interrogation tactics that could be used if approved by Sanchez.

Under the new order, which was issued Thursday, Sanchez and his staff will no longer consider any extraordinary interrogation methods other than putting prisoners alone in cells or in small groups segregated from the general prison population for more than 30 days. Regular interrogation techniques such as direct questioning of detainees without physical contact will remain allowable without special approval.

"What is said is simply, we will not even entertain a request" for anything more severe than segregation or isolation, "so don't even send it up for a review," said a senior Army official, one of two who briefed reporters on the condition of anonymity.

Sanchez issued the directive on the same day that Defense Secretary Donald H. Rumsfeld met with him on a surprise trip to Iraq. But Rumsfeld's chief spokesman, Larry DiRita, said yesterday that the defense secretary had not instructed the general to revise the policy.

Pressed by reporters on the reason for the change, DiRita acknowledged that "the heightened scrutiny of the last couple of weeks" may have played a role. But he also cited "a rigorous process" of periodic review that began long before the current scandal over the alleged abuse of detainees by U.S. soldiers and private contractors at Abu Ghraib, outside Baghdad.

Yesterday's briefing also provided the first detailed account of the evolution of the U.S. military's interrogation policy in Iraq. Until last autumn, U.S. forces in the country lacked a specific policy for questioning detainees.

"They relied upon the approaches that are contained within the Army field manual on interrogations," one Army official said.

That changed after a visit to Iraq in August and September by Maj. Gen. Geoffrey Miller, then the commander of the U.S. detention facility at Guantanamo Bay, Cuba, who came to assess interrogation practices. Among his recommendations was that commanders in Iraq adopt an explicit interrogation policy, the official said, and as a model, Miller left a copy of the policy for the Guantanamo facility.

That policy contained some measures more coercive than U.S. forces in Iraq could use, given orders to strictly abide by the Geneva Conventions, the official said.

"We used part of it and excepted other parts of it," he said. "That was the genesis for the first interrogation policy, which was put out in September."

After further review by the U.S. Central Command, a revised policy was issued Oct. 12. In one section, it listed approaches approved for all detainees, such as repeating questions over and over, staying silent, playing on a detainee's pride and telling detainees they could receive better treatment if they cooperate. Another section specified "safeguards," including a stipulation that all detainees be treated humanely.

The document also stated that use of any technique not explicitly listed required review by the senior intelligence officer and military lawyer on Sanchez's staff and approval by Sanchez.

On or about Oct. 18, the official said, an unidentified soldier in the 205th Military Intelligence Brigade, which operated at the Abu Ghraib facility, produced a one-page summary of the policy. It was titled "Interrogation Rules of Engagement" and hung on the wall of the Joint Interrogation and Debriefing Center.

That is the page released by the Senate Armed Services Committee on Tuesday. On the left it showed the list of generally approved interrogation methods, and on the right were the methods requiring Sanchez's approval. These included "dietary manipulation," "environmental manipulation," "sensory deprivation," "stress positions," disruptions in sleep patterns for up to 72 hours, isolation for longer than 30 days and the use of dogs.

These exceptional tactics had appeared in the September policy but ended up deleted from the October policy. Asked to explain the change, the official suggested it reflected reservations, either at the Central Command or elsewhere in the review process, about the acceptability of the more stressful measures or the advisability of enumerating them.

"There are reasonable people and very intelligent people who can differ on what is authorized, what's permissible, under the Geneva Conventions, particularly in the context of security internees," he said.

Nevertheless, he speculated that because the measures had appeared in the earlier policy and other draft papers, they were included in the now-famous summary sheet posted at the interrogation center.

Lt. Gen. Ricardo Sanchez will no longer hear requests to use certain coercive interrogation techniques.