The US Senate has approved a measure making clear the United States will not use torture against prisoners or detainees.

The measure, an amendment attached to an overall defense bill, would require Defense Secretary Donald Rumsfeld to issue guidelines to ensure that treatment of detainees meets standards set in U.S. law and in international agreements.

It would also require Mr. Rumsfeld to report any suspected violations to Congress. "I hope that this overwhelming support for this amendment at this moment in time will say to us across America who feel it is important to send this message, and to those listening around the world, that the United States still stands strong by its commitments to oppose torture and the cruel and inhuman and degrading treatment of detainees," said Senator Dick Durbin, an Illinois Democrat, a chief sponsor.

The Senate passed the amendment by voice vote, a week after Bush administration documents surfaced saying the government may not be bound by international anti-torture principles in the war on terrorism.

President Bush has maintained his policies adhere to the Geneva Conventions on the treatment of war prisoners.

The administration and the congress are investigating a prisoner abuse scandal at the Abu Ghraib prison in Iraq. Photographs of U.S. troops mistreating Iraqi detainees shocked the world.

The House of Representatives has not passed a similar amendment, and the two chambers will have to decide whether to include it in the final version of the defense bill.

In a related matter, the Senate voted (54-43) against another amendment that would have barred the Defense Department from using private contractors as prison interrogators.

Civilian contractors have been accused along with U.S. soldiers in the prisoner abuse scandal.

Supporters of the measure said it would help increase the Defense Department's accountability over its prisons. "This job of interrogation ought not to be done by private contractors," said Senator Chris Dodd, a Connecticut Democrat. "This inherently ought to be a government function, one that you do not "shop-out" or out-source, if you will, to others, where there is no accountability, no chain of command, no responsibility, virtual immunity if they do anything wrong under the uniform code of military justice."

The amendment called for withdrawing contract interrogators within 90 days, and contractors who are translators within a year.

Opponents, including the Chairman of the Senate Armed Services Committee, Republican Senator John Warner of Virginia, said the measure would hurt intelligence operations in Iraq, Afghanistan, and U.S. facilities at Guantanamo Bay, Cuba, where private contractors are involved in directing or conducting interrogations. "That cripples America's intelligence system in the middle of a war," he said.

The Senate is expected to pass the overall defense bill in the coming days.