A classified Justice Department (search) investigation determined that a whistle-blower's allegations of security lapses in the FBI's translator program were at least partly responsible for her firing, the FBI director told U.S. senators.

The agency's inspector general, Glenn Fine, did not conclude that the FBI had retaliated against the translator, Sibel Edmonds (search), when it fired her in April 2002, FBI Director Robert Mueller (search) wrote in a July 21 letter to the Senate Judiciary Committee, obtained Thursday by The Associated Press.

But Mueller acknowledged he was concerned by Fine's determination that allegations by Edmonds "were at least a contributing factor in why the FBI terminated her services," the director wrote, quoting from the classified report.

Edmonds alleges she was fired after complaining to FBI managers about shoddy wiretap translations and told them an interpreter with a relative at a foreign embassy might have compromised national security after the Sept. 11, 2001 terror attacks by passing information from an FBI wiretap to the target of an investigation.

The Justice Department's report concluded the FBI failed to adequately pursue Edmonds' allegation that her colleague committed espionage, Mueller disclosed in the letter. The director said the FBI conducted a "relevant investigation," but he promised to review the case and conduct a further investigation if necessary.

Mueller said he asked the inspector general to help determine whether any FBI employees should face disciplinary action, and he promised to report such an outcome to the Judiciary Committee.

A U.S. district judge earlier this month dismissed Edmonds' lawsuit against the government over her firing because he agreed with claims by Attorney General John Ashcroft and a senior FBI official that a suit could expose intelligence-gathering methods and disrupt diplomatic relations with foreign governments.

Edmonds is appealing that ruling.

Mueller told senators that the Justice Department investigation into Edmonds' firing, which remains classified, determined that Edmonds never qualified for formal whistle-blower protection because she was a contract worker, not a full-time FBI employee.

But Mueller promised to write another bureau-wide memorandum warning supervisors against retaliating against employees who reveal internal problems.

"I want all FBI employees, as well as our contractors and detailees, to know that I encourage them to raise good-faith concerns about mismanagement or misconduct," Mueller wrote.

Sens. Patrick Leahy, D-Vt., and Charles Grassley, R-Iowa, have said they will ask the Justice Department to release an unclassified version of the inspector general's report.