WASHINGTON (Reuters) - U.S. Attorney General Michael Mukasey said on Thursday that he is working to revise the guidelines for FBI investigations as the bureau seeks to transform itself into an intelligence-gathering agency that seeks to prevent terrorist attacks.

U.S. Attorney General Michael Mukasey pauses during his address to the Commonwealth Club in San Francisco, California March 27, 2008. REUTERS/Robert Galbraith

Meeting with reporters at the Justice Department, Mukasey said for the first time that he is working on revising the guidelines, but declined to discuss possible changes. It was unclear when the review would be finished.

In May 2002 then-Attorney General John Ashcroft announced sweeping changes to the guidelines to give the FBI greater leeway to conduct domestic counterterrorism surveillance.

A quarter century after the government sought to curtail domestic spying by imposing the guidelines, Ashcroft announced a complete overhaul, lifting restrictions on the FBI conducting surveillance at public gatherings, on religious and political organizations and on surfing the Internet.

Civil liberties groups widely criticized the changes.

The attorney general’s guidelines on surveillance were first imposed on the FBI in the 1970s following disclosures that the bureau under the late J. Edgar Hoover had run a widespread domestic surveillance program that spied on civil rights activists and political opponents.

Mukasey said the guidelines needed to be changed “because it’s necessary to put in place regulations that will allow the FBI to transform itself ... to an intelligence-gathering organization in addition to just a crime-solving organization.”

He also said he wanted to ensure “coherent regulations across the board” so the guidelines in one area do not conflict with the rules in another area.

Justice Department spokesman Peter Carr later said the FBI operates under several sets of guidelines, including one for criminal investigations and another for national security investigations.

“As there are differences with the standards and guidance governing certain core FBI activities, the attorney general has begun an effort to review these guidelines,” Carr said.