AS EVIDENCE of prisoner mistreatment at Guantanamo Bay began to mount in 2002, FBI agents at the base created a "war crimes file" to document accusations against American military personnel, but were eventually ordered to close the file down, a Justice Department report has disclosed.

The report, a 437-page review prepared by the Justice Department inspector-general, provides the fullest account to date of internal dissent and confusion within the Bush Administration over the use of harsh interrogation tactics by the military and the Central Intelligence Agency.

In one of several previously undisclosed episodes, the report found that US 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, a female interrogator reportedly bent back an inmate's thumbs and squeezed his genitals as he grimaced in pain.