A Justice Department investigation has found that FBI agents, including several supervisors, cheated on an important test covering the bureau's policies for conducting surveillance on Americans.

Justice Department Inspector General Glenn Fine said Monday that his limited review of allegations that agents improperly took the open-book test together or had access to an answer sheet has turned up "significant abuses and cheating."

Fine called on the bureau to discipline the agents, throw out the results and come up with a new test to see if FBI agents understand new rules allowing them to conduct surveillance and open files on Americans without evidence of criminal wrongdoing.

FBI Director Robert Mueller said that in cases in which misconduct has been determined, personnel actions were taken, and that process continues.

"We will follow up in each of the 22 cases the IG has found for disciplinary action, as appropriate, as well as any other allegations of misconduct," the FBI director said in a statement. Mueller said that when allegations of misconduct "first came to our attention, we moved quickly to investigate, bringing in the Office of Inspector General."

The troubling review of the exam on surveillance rules follows Fine's report last week on the FBI's scrutiny of domestic activist groups. That investigation found that the FBI gave inaccurate information to Congress and the public when it claimed a possible terrorism link to justify monitoring an anti-war rally in Pittsburgh in 2002. That IG report also criticized the factual basis for opening or continuing FBI domestic terrorism investigations of some other nonviolent left-leaning groups.

In the inquiry into the exam, the inspector general looked only at four FBI field offices and found enough troubling information to warrant a comprehensive review by the FBI.

In one FBI field office, four agents exploited a computer software flaw "to reveal the answers to the questions as they were taking the exam," Fine said.

Other test-takers used or circulated materials that essentially provided the test answers, he said.

Fine said that almost all of those who cheated "falsely certified" that they did the work themselves, without the help of others.

Last year, Assistant Director Joseph Persichini, the head of the FBI's Washington field office that investigates congressional wrongdoing and other crime in the nation's capital, retired amid a review of test-taking in his office.

Persichini wrote down the answers to the test while two of his most senior managers were in the room taking the exam together, the IG said. Persichini used the answers he had written down to complete the exam another day, the IG added. A legal adviser also was in the room with Persichini and the two agents discussing the questions and possible answers.

Sen. Chuck Grassley, R-Iowa, said he was "especially disheartened that several FBI supervisors cheated on this exam" and the senator called on the FBI to implement "a more trustworthy exam process going forward and hold accountable those responsible for the cheating."

Most FBI employees took the exam between May 2009 and January 2010.

"This report reinforces that the FBI cannot police itself," said Michael German, policy counsel to the American Civil Liberties Union. "There needs to be stronger oversight and stronger controls over the bureau's use of its investigative powers."

German also expressed concern about the surveillance guidelines themselves, saying they enable the targeting of people for investigation when there is "no factual basis to support that speculative belief."

An FBI professional organization said Monday it supported changes to ensure the integrity of future tests.

"We look forward to working with the bureau to develop better procedures to ensure that future exams are conducted in a uniform manner with clear and consistent instruction in all locations," said Konrad Motyka, president of the FBI Agents Association, which has membership of nearly 12,000 active and retired agents.