In one of several previously undisclosed episodes, the report found that American military interrogators appeared to have collaborated with visiting Chinese officials at Guantanamo Bay to disrupt the sleep of Chinese Muslims held there, waking them every 15 minutes the night before their interviews by the Chinese. In another incident, it said, a female interrogator reportedly bent back an inmate's thumbs and squeezed his genitals as he grimaced in pain.
The report describes what one official called "trench warfare" between the F.B.I. and the military over the rough methods being used on detainees in Guantanamo Bay, Afghanistan and Iraq.
The report says that the F.B.I. agents took their concerns to higher-ups, but that their concerns often fell on deaf ears: officials at senior levels at the F.B.I., the Justice Department, the Defense Department and the National Security Council were all made aware of the F.B.I. agents' complaints, but little appears to have been done as a result.
The report quotes passionate objections from F.B.I. officials who grew increasingly concerned about the reports of practices like intimidating inmates with snarling dogs, parading them in the nude before female soldiers, or "short-shackling" them to the floor for many hours in extreme heat or cold.
Such tactics, said one F.B.I. agent in an e-mail message to supervisors in November 2002, might violate American law banning torture.
More senior officials, including Spike Bowman, who was then the head of the national security law unit at the F.B.I., tried to sound the alarm as well.
"Beyond any doubt, what they are doing (and I don't know the extent of it) would be unlawful were these enemy prisoners of war," Mr. Bowman wrote in an e-mail message to top F.B.I. officials in July 2003.