The order bars some practices such as sexual abuse, part of an effort to quell international criticism of some of the CIA's most sensitive and debated work. It does not say what practices would be allowed.

The executive order is the White House's first public effort to reach into the CIA's five-year-old terror detention program, which has been in limbo since a Supreme Court decision last year called its legal foundation into question.

Officials would not provide any details on specific interrogation techniques that the CIA may use under the new order. In the past, its methods are believed to have included sleep deprivation and disorientation, exposing prisoners to uncomfortable cold or heat for long periods, stress positions and - most controversially - the simulated drowning technique known as waterboarding.

The Bush administration has portrayed the interrogation operation as one of one of its most successful tools in the war on terror, while opponents have said the agency's techniques have left a black mark on the United States' reputation around the world.

Bush's order requires that CIA detainees "receive the basic necessities of life, including adequate food and water, shelter from the elements, necessary clothing, protection from extremes of heat and cold, and essential medical care."

A senior intelligence official would not comment directly when asked if waterboarding would be allowed under the new order and under related - but classified - legal documents drafted by the Justice Department.

However, the official said, "It would be wrong to assume the program of the past transfers to the future."

A second senior administration official acknowledged sleep is not among the basic necessities outlined in the order.

Both officials spoke on condition of anonymity to discuss the order more freely.

Skeptical human rights groups did not embrace Bush's effort.

Tom Malinowski, Washington director for Human Rights Watch, said the broad outlines in the public order don't matter. The key is in the still-classified guidance distributed to CIA officers.

As a result, the executive order requires the public to trust the president to provide adequate protection to detainees. "Given the experience of the last few years, they have to be naive if they think that is going to reassure too many people," he said.

The order specifically refers to captured al-Qaida suspects who may have information on attack plans or the whereabouts of the group's senior leaders. White House press secretary Tony Snow said the CIA's program has saved lives and must continue on a sound legal footing.

"The president has insisted on clear legal standards so that CIA officers involved in this essential work are not placed in jeopardy for doing their job - and keeping America safe from attacks," he said.

The five-page order reiterated many protections already granted under U.S. and international law. It said that any conditions of confinement and interrogation cannot include:

¡¤Torture or other acts of violence serious enough to be considered comparable to murder, torture, mutilation or cruel or inhuman treatment.

¡¤Willful or outrageous acts of personal abuse done to humiliate or degrade someone in a way so serious that any reasonable person would "deem the acts to be beyond the bounds of human decency." That includes sexually indecent acts.

¡¤Acts intended to denigrate the religion of an individual.

The order does not permit detainees to contact family members or have access to the International Committee of the Red Cross.

In a decision last year aimed at the military's tribunal system, the Supreme Court required the U.S. government to apply Geneva Convention protections to the conflict with al-Qaida, shaking the legal footing of the CIA's program.

Last fall, Congress instructed the White House to draft an executive order as part of the Military Commissions Act, which outlined the rules for trying terrorism suspects. The bill barred torture, rape and other war crimes that clearly would have violated the Geneva Conventions, but allowed Bush to determine - through executive order - whether less harsh interrogation methods can be used.

The administration and the CIA have maintained that the agency's program has been lawful all along.

In a message to CIA employees on Friday, Director Michael Hayden tried to stress the importance and narrow scope of the program. He noted that fewer than half of the less than 100 detainees have experienced the agency's "enhanced interrogation measures."

"Simply put, the information developed by our program has been irreplaceable," he said. "If the CIA, with all its expertise in counterterrorism, had not stepped forward to hold and interrogate people like (senior al-Qaida operatives) Abu Zubaydah and Khalid Sheikh Mohammed, the American people would be right to ask why."

For decades, the United States had two paths for questioning suspects: the U.S. justice system and the military's Army Field Manual.

However, after the 9/11 attacks, the Bush administration decided more needed to be done. With Zubaydah's capture in 2002, the CIA program was quietly created.

Since then, 97 terror suspects are believed to have been held by the agency at locations around the world, often referred to as "black sites."

The program sparked international controversy as details slowly emerged, with human rights groups saying the agency's work was a violation of international law, including the Third Geneva Convention's Common Article 3 protections, which set a baseline standard for the treatment of prisoners of war.

In September, Bush announced the U.S. had transferred the last 14 high-value CIA detainees to the military's detention facility at Guantanamo Bay, Cuba, where they would stand trial. The CIA has held one detainee since then - an Iraqi who the U.S. considered one of al-Qaida's most senior operatives. He was also eventually transferred to Guantanamo.