May 20 (Bloomberg) -- U.S. FBI agents refused in most cases to employ harsh interrogation techniques on terror suspects, raising objections about the military's use of sleep deprivation, snarling dogs and other tactics, a new report finds.

Still, the study released today by Justice Department Inspector General Glenn Fine faulted the Federal Bureau of Investigation for being slow to provide guidelines on how agents should report evidence of prisoner mistreatment to superiors. The review looked at the behavior of more than 1,000 FBI employees sent to Iraq, Afghanistan and the U.S. Navy base in Guantanamo Bay, Cuba, following the Sept. 11 attacks.

``The FBI could have provided clearer guidance earlier and pressed harder its concerns about detainee abuse by other agencies,'' Fine said in a statement. ``But we believe the FBI should be credited for its conduct and professionalism.''

Fine's audit doesn't assess the conduct of CIA or Defense Department interrogators and says FBI agents never witnessed the use of simulated drowning, or waterboarding. While praising the FBI, the report's description of aggressive questioning of al- Qaeda suspects may fuel congressional investigations of Bush administration anti-terror policies.

Senator Patrick Leahy, a Vermont Democrat and chairman of the Judiciary Committee, said he plans to hold hearings on the issue.

``The inspector general's report raises troubling questions about whether other government agencies, including the Department of Defense, are following established policies for the treatment of detainees,'' Leahy said.

`Deaf Ears'

New York Democratic Representative Jerrold Nadler, whose House Judiciary subcommittee is probing the administration's interrogation rules, said today's review shows that complaints about prisoners' treatment by FBI employees ``fell on deaf ears'' when they reached headquarters.

``The leadership at the FBI and the Justice Department failed to meet the opportunity and obligation to end the torture of detainees,'' Nadler said. ``The admirable actions taken by those brave FBI agents willing to speak out were undermined by those who led them.''

Nevertheless, the review represents a bit of positive news for the FBI, which has regularly come under fire from lawmakers for misusing its powers to investigate terrorism. Fine's office has issued a series of reports critical of the bureau, including findings of widespread violations of the rules for obtaining telephone, e-mail, financial and other records in national security probes.

Abu Ghraib

In today's report, Fine said FBI Director Robert Mueller decided in 2002 that the agency wouldn't participate in questioning that used aggressive techniques. It wasn't until 2004, after the revelations of prisoner mistreatment at Abu Ghraib prison in Iraq, that the FBI required agents to report when they witnessed abuse of detainees.

The 370-page study, with some sections blacked out because they contain classified information, also details frequent disputes between FBI agents and their counterparts at the Defense Department and the Central Intelligence Agency over how high- level al-Qaeda captives should be interviewed.

The FBI, in a statement, said it was ``gratified'' that Fine concluded its agents acted professionally.

``FBI policy is to employ the same non-coercive, rapport- based interview techniques to detainees encountered in military zones that we employ every day in every aspect of our mission,'' the statement said. ``The IG's report confirms that the FBI chose not to participate with other government agencies in joint interrogations in which techniques not allowed by the FBI in the United States were used.''

Suing Federal Agencies

The American Civil Liberties Union, which is suing federal agencies for documents relating to treatment of detainees, said the report shows that top FBI and Justice Department officials should have stepped in to stop the coercive questioning.

``Senior officials failed to act aggressively to end the abuses,'' said Amrit Singh, an ACLU lawyer in New York. ``The leadership was more concerned with avoiding responsibility than with enforcing the law.''

To contact the reporter on this story: Robert Schmidt in Washington at rschmidt5@bloomberg.net.

Last Updated: May 20, 2008 15:25 EDT