WASHINGTON (AP) _ The FBI is making a serious attempt to correct problems in its crime lab, which had been accused of mishandling evidence, the Justice Department's inspector general told a Senate subcommittee Monday.

Inspector General Michael Bromwich said it is too early to tell whether all recommendations made in a damaging report he issued earlier this year have been fully implemented.

But further investigation of reports of additional misconduct would be counterproductive now, Bromwich said in written testimony submitted to the Senate Judiciary Committee's panel on administrative oversight and the courts.

``It is in my judgment not appropriate or advisable for us _ or any other outside entity _ to do so at this time,'' Bromwich said. ``The FBI laboratory is in the midst of trying to implement significant change while under a public microscope.''

In a 517-page report released in April, Bromwich's agency said it found evidence of errors, substandard analysis and deficient practices.

Bromwich also said that although he was grateful to Frederic Whitehurst, the whistleblower who brought the problems to public attention, many of his allegations were exaggerated or false and his office recommended that Whitehurst not be allowed to return to his job at the lab.

``We concluded that Dr. Whitehurst could no longer effectively function in the laboratory and recommended that the FBI consider what role, if any, he could usefully serve in other components of the FBI,'' Bromwich said.

Other witnesses at the hearing _ some of them current FBI employees _ said lab problems were largely confined to its explosives unit, where a handful of employees may have gotten carried away with their elite status.

A retired lab unit chief described how a unit supervisor altered information in evidence reports so that they made a better case for prosecutors. Although management knew of this, the supervisor later was promoted, said James Corby, who retired in 1995.

Corby said he knew of no trial in which the faulty information was so pivotal it was responsible for the conviction of an innocent person, although ``we may never know.''

The subcommittee chairman, Sen. Chuck Grassley, R-Iowa, accused FBI upper management of being more concerned with image than substance and said FBI Director Louis Freeh was not cooperating with his subcommittee's efforts to oversee the agency.

``The FBI's say-one-thing-do-another habit is precisely what gives me pause in accepting assurances that the lab is under control,'' Grassley said. ``The problems exist and flourish because of a cultural disease within the FBI. That culture is preserved by FBI management, both within the lab and higher up.''

The National Association of Criminal Defense Lawyers said it believes that lab problems are far worse than the ones Bromwich described.

``Our review of documents thus far generated by the Department of Justice inspector general's 18-month investigation of the FBI lab reveals systematic problems scarcely addressed by the April 15 report _ bad science, sloppy recordkeeping and professional misconduct,'' said Gerald Lefcourt, the group's president.

``So far we've only seen the tip of the iceberg,'' he said. ``We are greatly concerned that for some American citizens convicted by bad science, the time for filing appeals and writs of habeas corpus is fast running out.''