The FBI crime laboratory produced scientifically flawed reports and inaccurate testimony in several major cases, including the World Trade Center and Oklahoma City bombings, according to a Justice Department report that recommends a thorough overhaul of the nation's leading forensic facility.

Despite its harsh criticism of some FBI personnel and demands for institutional change, the 500-page report by the Justice Department's inspector general cleared laboratory examiners of allegations that they committed perjury and fabricated evidence -- the most serious charges to surface during the 18-month inquiry.

FBI Deputy Director William J. Esposito said at a news conference that although "very serious" problems had been uncovered in the forensic laboratory, the FBI could remedy them by implementing all of the inspector general's recommendations, including measures that would submit the FBI to an unprecedented degree of outside scrutiny.