Three senators want the Justice Department to investigate claims that the FBI retaliated against an Arab-American agent by passing him over for top counterterrorism jobs despite his expertise.

Sens. Arlen Specter, R-Pa., Patrick Leahy, D-Vt., and Chuck Grassley, R-Iowa, urged the Justice Department's inspector general to determine whether the FBI denied a promotion to agent Bassem Youssef after Youssef complained about FBI management to another member of Congress, Rep. Frank Wolf, R-Va.

Specter is chairman of the Judiciary Committee, and Leahy is the panel's senior Democrat.

In a joint letter this week to Inspector General Glenn Fine, the senators warned that "retaliation for such disclosures sends a chilling message to all employees and thus prevents both the (FBI) director and Congress from receiving valuable information necessary to run and oversee the bureau effectively."

Fine's office said it was reviewing the senators' request.

Youssef, considered by some to be one of the FBI's most accomplished counterterrorism agents before the September 2001 attacks, has separately filed a discrimination lawsuit.

In a deposition related to the lawsuit, Deputy Assistant Director John Lewis said he was shocked over Youssef's decision to complain to FBI Director Robert Mueller during a meeting in Wolf's office.

"To put the director of the FBI in that position, to show him that lack of courtesy, to surprise him with a member of Congress in my judgment is absolutely outrageous," Lewis told Youssef's lawyer during questioning in May 2005. "It shows a tremendous disloyalty to the director."

The bureau said Mueller does not tolerate retribution but otherwise declined to comment on the letter by senators, citing the pending litigation.

"It would be inappropriate to make any comment. However, it is important to add that Director Mueller has stated the FBI will not tolerate any form of retribution against any employees and that the Bureau strives to treat every person fairly and professionally," the FBI said in a statement.