The report, an account alleging physical and psychological brutality inside CIA "black site" prisons, also states that some U.S. practices amounted to "cruel, inhuman or degrading treatment." Such maltreatment of detainees is expressly prohibited by the Geneva Conventions.

The findings were based on an investigation by ICRC officials, who were granted exclusive access to the CIA's "high-value" detainees after they were transferred in 2006 to the U.S. detention camp at Guantanamo Bay, Cuba. The 14 detainees, who had been kept in isolation in CIA prisons overseas, gave remarkably uniform accounts of abuse that included beatings, sleep deprivation, extreme temperatures and, in some cases, waterboarding, or simulating drowning.

At least five copies of the report were shared with the CIA and top White House officials in 2007 but barred from public release by ICRC guidelines intended to preserve the humanitarian group's strict policy of neutrality in conflicts. A copy of the report was obtained by Mark Danner, a journalism professor and author who published extensive excerpts in the April 9 edition of the New York Review of Books, released yesterday. He did not say how he obtained the report.

"The ill-treatment to which they were subjected while held in the CIA program, either singly or in combination, constituted torture," Danner quoted the report as saying.

Many of the details of alleged mistreatment at CIA prisons had been reported previously, but the ICRC report is the most authoritative account and the first to use the word "torture" in a legal context.

The CIA declined to comment. A U.S. official familiar with the report said, "It is important to bear in mind that the report lays out claims made by the terrorists themselves."

Often using the detainee's own words, the report offers a harrowing view of conditions at the secret prisons, where prisoners were told they were being taken "to the verge of death and back," according to one excerpt. During interrogations, the captives were routinely beaten, doused with cold water and slammed head-first into walls. Between sessions, they were stripped of clothing, bombarded with loud music, exposed to cold temperatures, and deprived of sleep and solid food for days on end. Some detainees described being forced to stand for days, with their arms shackled above them, wearing only diapers.

"On a daily basis . . . a collar was looped around my neck and then used to slam me against the walls of the interrogation room," the report quotes detainee Tawfiq bin Attash, also known as Walid Muhammad bin Attash, as saying. Later, he said, he was wrapped in a plastic sheet while cold water was "poured onto my body with buckets." He added: "I would be wrapped inside the sheet with cold water for several minutes. Then I would be taken for interrogation."

ICRC officials did not dispute the authenticity of the excerpts, but a spokesman expressed dismay over the leak of the material. "We regret information attributed to the ICRC report was made public in this manner," spokesman Bernard Barrett said.

"The ICRC has been visiting the detainees formerly held by the CIA," he added, "at Guantanamo since 2006. Any concerns or observations the ICRC had when visiting the detainees are part of a confidential dialogue."

President George W. Bush acknowledged the use of coercive interrogation tactics on senior al-Qaeda captives detained by the CIA in the aftermath of the Sept. 11, 2001, terrorist attacks, but he insisted that the measures complied with U.S. and international law. Former CIA director Michael V. Hayden confirmed last year that the measures included the use of waterboarding on three captives before 2003.

President Obama outlawed such practices within hours of his inauguration in January. But Obama has expressed reluctance to conduct a legal inquiry into the CIA's policies.