FBI agents documented more than two dozen incidents of possible mistreatment at the Guantanamo Bay military base, including one detainee whose head was wrapped in duct tape for chanting the Koran and another who pulled out his hair after hours in a sweltering room.

Documents released Tuesday by the FBI offered new details about the harsh interrogation practices used by military officials and contractors when questioning so-called enemy combatants.

The reports describe a female guard who detainees said handled their genitals and wiped menstrual blood on their face. Another interrogator reportedly bragged to an FBI agent about dressing as a Catholic priest and "baptizing" a prisoner.

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The FBI reports do not say whether any laws were broken. They said nothing employees observed rose to the level of abuse seen at the Abu Ghraib prison in Iraq.

Some military officials and contractors told FBI agents that the interrogation techniques had been approved by the Defense Department, including directly by former Defense Secretary Donald H. Rumsfeld.

The documents were released in response to a public records request by the American Civil Liberties Union, which is suing Rumsfeld and others on behalf of former military detainees who say they were abused. Many of the incidents in the FBI documents have already been reported and are summarized in the ACLU's lawsuit.

Defense Department spokesman Lt. Cmdr. Joe Carpenter said the issues raised in the report are not new. A dozen reviews of detention operations have found no policies that condone abuse, he said.

The treatment of detainees has long been a volatile subject, especially between the administration and the Democratic lawmakers slated to assume the majority when the 110th Congress convenes on Thursday.

One incoming chairman served notice Tuesday that the issue is a top priority. Senate Judiciary Committee Chairman Patrick Leahy, D-Vt., notified Attorney General Alberto Gonzales that his panel's first oversight hearing of the new Congress would focus on two documents Leahy is seeking about the interrogation methods of another agency, the CIA.

The Justice Department has refused to hand over the documents, saying their contents are "extremely sensitive" and could help terrorists plot more attacks.

President Bush signed legislation in October that authorized aggressive interrogation tactics but did not define them. ACLU lawyer Jameel Jaffer said the court documents show that stricter congressional oversight is needed.

"If you just authorize in a vague way, there's no end to the abusive methods the interrogators will come up with," Jaffer said.

The records were gathered as part of an internal FBI survey in 2004 and are not part of a criminal investigation.

The agency asked 493 employees whether they witnessed aggressive treatment that was not consistent with the FBI's policies. The bureau received 26 positive responses, including some from agents who were troubled by what they saw.

"I did observe treatment that was not only aggressive but personally very upsetting," one agent wrote, describing seeing a man left in a 100-degree room with no ventilation overnight. "The detainee was almost unconscious on the floor with a pile of hair next to him. He had apparently literally been pulling his own hair out throughout the night."

Another agent said he heard several "thunderclaps" then saw a detainee lying on the floor with a bloody nose. Interrogators told the agent the man was upset and had thrown himself to the floor.

In one report, an agent said he saw a detainee draped in an Israeli flag in a room with loud music and strobe lights. A note on the report said the Israeli flag "may be over the top but not abusive." The words "may be" were then crossed out and replaced with "is."

Carpenter, the Pentagon spokesman, said the Guantanamo detainees "include some of the world's most vicious terrorist operatives."

"The Department of Defense policy is clear," Carpenter said. "We treat detainees humanely. The United States operates safe, humane and professional detention operations for enemy combatants who are providing valuable information in the war on terror."

FBI spokesman Richard J. Kolko said all the information in the reports was passed on to the Pentagon's inspector general.

A federal judge is considering whether to allow the ACLU's lawsuit against Rumsfeld to go forward. Government officials are normally shielded from personal lawsuits related to their jobs.

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