SAN JUAN, Puerto Rico – U.S. Special Forces accused of abusing prisoners in Iraq threatened Defense Intelligence Agency personnel who saw the mistreatment and once confiscated photos of a prisoner who had been punched in the face, according to American government memos released yesterday by the American Civil Liberties Union.

The Special Forces also monitored email messages sent by Defense personnel and ordered them “not to talk to anyone” in America about what they saw, said one memo written by the Defense Intelligence Agency chief, who complained to his Pentagon bosses about the harassment.

Prisoners arriving at a detention center in Baghdad had “burn marks on their backs,” as well as bruises, and some complained of kidney pain, according to the June 25, 2004, memo.

FBI agents also reported seeing detainees at Abu Ghraib subjected to sleep deprivation, humiliation, and forced nudity between October and December 2003 – when the most serious abuses allegedly took place in a scandal that remains under investigation.

The release of the ACLU documents comes a day after The Associated Press reported that a senior FBI official wrote a letter to the Army’s top criminal investigator complaining about “highly aggressive” interrogation techniques at the American prison camp in Guantanamo Bay dating back to 2002 – more than a year before the scandal broke at the Iraqi prison.

The memos reveal behind-the-scenes tensions between the FBI and American military and intelligence task forces running prisoner interrogations at Guantanamo and in Iraq as the Bush administration sought better intelligence to fight terrorists and the deadly Iraq insurgency.

“These documents tell a damning story of sanctioned government abuse – a story that the government has tried to hide and may well come back to haunt our own troops captured in Iraq,” said the executive director of the New York-based ACLU, Anthony D. Romero.

The documents were released only after a federal court ordered the Pentagon and other government agencies to comply with a year-old request filed under the Freedom of Information Act by the ACLU, the Center for Constitutional Rights, Physicians for Human Rights, Veterans for Common Sense, and Veterans for Peace.

A spokesman for U.S. Central Command in Tampa, Fla., which directs special military operations in Iraq and Afghanistan, declined to comment on specific allegations.

“We take all issues of detainee abuse very seriously, and where there is the potential that these abuses could have taken place, we investigate them,” said Navy Lieutenant Commander Nick Balice.

Joe Navarro, a retired FBI agent who teaches interrogation techniques to the military and is familiar with interrogations at Guantanamo, said using threats during interrogations only stands to taint information gleaned from the sessions. “The only thing that torture guarantees is pain,” Mr. Navarro told The Associated Press yesterday. “It never guarantees the truth.”

Many memos refer to Major General Geoffrey D. Miller, whose mission as head of the Guantanamo prison from October 2002 was to improve the intelligence gleaned from terror suspects. In August 2003, General Miller was sent to Iraq to make recommendations on interrogation techniques to get more information out of prisoners. He was posted to Abu Ghraib in March 2004.

One FBI e-mail released by the ACLU said General Miller “continued to support interrogation strategies [the FBI] not only advised against, but questioned in terms of effectiveness.”

General Miller left Iraq yesterday for a new assignment in Washington, with responsibility for Army housing and other support operations, and could not be reached for comment.

According to the memo from the Defense Intelligence chief, Vice Admiral Lowell Jacoby, a Special Forces task force in Iraq threatened Defense personnel who complained about abuses. Some had their car keys confiscated and were ordered not to leave the base “even to get a haircut.”

Commander Balice refused to describe the task force, which could include Army Rangers, Delta Force, Navy SEALs, and other Special Forces soldiers working with CIA operatives.

Another June 25 memo describes how a task force officer punched a prisoner in the face “to the point he needed medical attention,” failed to record the medical treatment, and confiscated photos of the injuries. The date of the incident wasn’t clear, as the memo – like others released by the ACLU – had been heavily redacted to remove dates and names.