WASHINGTON - The Bush administration, bowing to court edict and political pressure, guaranteed the basic protections of the Geneva Conventions to captives in the war on terrorism and asked lawmakers Tuesday to restore the military tribunals now in limbo.

As senators took up the prickly question of how suspected terrorists should be treated and tried, the administration disclosed it had ordered a review of military detention practices to make sure they comply with Geneva standards.

The administration has refused to grant Geneva status to the detainees held at Guantanamo Bay, Cuba, and elsewhere, saying they were not from a recognized nation, were not captured in uniform and did not observe traditional rules of war.

Instead, the people apprehended in Afghanistan, Pakistan and other zones in the war on terrorism have been classified as "unlawful combatants." The Supreme Court last month invalidated the tribunals handling these cases, ruling they defied international law and had not been authorized by Congress.

The administration sought remedies on both fronts Tuesday, revisiting its prisoner guarantees and appealing to senators to revive the tribunals with legislation. Some critics have suggested the detainees should be tried by military courts-martial instead, an idea opposed by President Bush.

The Senate is unlikely to act until the fall, setting up a pitched debate over the issue at the height of the campaign for control of Congress.

A memo from Deputy Defense Secretary Gordon England to all branches of the armed forces, released Tuesday, instructed them to ensure that all Defense Department policies, practices and directives comply with Article 3 of the Geneva Conventions governing the humane treatment of prisoners.

The practical effect on interrogation techniques, detention conditions and trial procedures was unclear.

Officials at the White House and Pentagon did not say how, if at all, the treatment of terror detainees would be different under the Geneva Conventions. The government has long insisted that its treatment of these captives has been in compliance with the Geneva treaties all along, even though it has refused to apply them as a matter of law.

Steven Bradbury, acting assistant attorney general for the Justice Department's Office of Legal Counsel, told a Senate hearing that Article 3 is ambiguous and its use "will create a degree of uncertainty for those who fight to defend us from terrorist attack."

Even so, he said, the Supreme Court imposed a standard "that we must now interpret and implement."

Article 3 prohibits "outrages upon personal dignity, in particular humiliating and degrading treatment," as well as torture and "cruel treatment." It requires sentences to be passed by a "regularly constituted court affording all the judicial guarantees which are recognized as indispensable by civilized peoples."

For all the new emphasis on Geneva protections, the memo did not expressly revoke Bush's directive in February 2002 that "common Article 3 of Geneva does not apply to either al-Qaida or Taliban detainees."

Instead, it noted that the Supreme Court has determined Article 3 "applies as a matter of law to the conflict with al-Qaida," and said existing standards and procedures, except for the military commissions, already should be in compliance the article.

Administration officials testifying to the Senate Judiciary Committee asked for legislation to codify tribunal procedures so they can pass constitutional muster and still give the U.S. flexibility to deal with an unconventional foe.

"We would like to see Congress act quickly to establish a solid statutory basis for the military commission process, so that trials of captured al-Qaida terrorists can move forward again," Bradbury said. "The United States may continue to detain the terrorists we have captured. But as of right now, we cannot effectively punish those who have committed war crimes. That is unacceptable."

Senators were told that some 1,000 suspected terrorists are in U.S. detention around the world, including about 450 at Guantanamo. Prisoners from the Iraq war are already dealt with under the Geneva Conventions.

Administration officials cautioned against adopting a version of the military court-martial to try suspected terrorists, saying that system is in some ways more open and generous to defendants than even the civilian code. Interrogations could be deterred, for example, if terrorists were granted the court-martial right to avoid speaking until represented by counsel.

Republican Sen. Arlen Specter of Pennsylvania, the committee chairman, opened the hearing by saying, "We're not going to give the Department of Defense a blank check."

Sen. Patrick Leahy of Vermont, the committee's top Democrat, said "kangaroo court procedures" must be changed and any military commissions "should not be set up as a sham. They should be consistent with a high standard of American justice, worth protecting."

Guantanamo has been a flashpoint for both U.S. and international debate over the treatment of detainees without trial and over allegations of torture, denied by U.S. officials. Even U.S. allies have criticized the facility and process.

The camp came under worldwide condemnation after it opened more than four years ago, when pictures showed prisoners kneeling, shackled and being herded into wire cages. It intensified with reports of heavy-handed interrogations, hunger strikes and suicides.

Snow insisted that all U.S. detainees have been treated humanely. Still, he said, "We want to get it right."

Jumana Musa, advocacy director for Amnesty International USA, said the effect of the new policy on prisoner treatment is unclear, because questionable tactics have been employed despite existing requirements for humane treatment.

"This could change nothing except for the fact that it is an admission for the first time that any law applies to al-Qaida detainees," she said. "The issue here is really one of interpretation, and we've seen how they've interpreted torture."

The Financial Times reported the new memo before its release.