WASHINGTON — A new Justice Department report praises the refusal of F.B.I. agents to take part in the military’s abusive questioning of prisoners in Guantánamo Bay, Iraq and Afghanistan, but it also finds fault with the bureau’s slow response to complaints about the tactics from its own agents, people with knowledge of the still-secret report said.

The department inspector general’s office is expected to conclude that no agents for the Federal Bureau of Investigation took part in the military’s rough interrogations, a key validation for the bureau, officials said. “The F.B.I. should be credited for its conduct and professionalism in detainee interrogations in the military zones,” the inspector general said in one section of the report, which is likely to be released publicly next week.

At the same time, however, the report is also expected to say that the F.B.I. was sometimes too slow to respond to what were often serious misgivings from its agents about interrogation tactics, officials said, and that it lacked clear guidelines and training on how such complaints should have been handled.

The F.B.I. stationed agents at Guantánamo Bay and other military detention sites to assist in the questioning of detainees taken into custody after Sept. 11, but the rough tactics by military interrogators soon became a major source of friction between the bureau and sister agencies. F.B.I. agents complained to superiors beginning in 2002 that the tactics they had seen yielded little actual intelligence, prevented them from establishing a rapport with detainees through more traditional means of questioning and might violate F.B.I. policy or American law.