Over all, the transcripts and summaries suggest that the F.B.I.'s procedures for testing explosive material were lax and that nonscientists who managed the laboratory appeared to be casual in their approach to handling evidence. The criticism closely parallels that of Frederic Whitehurst, an F.B.I. chemist who has been critical of the laboratory. The criticism suggests that the procedures in specific cases like the Oklahoma City bombing illustrate wider problems at a laboratory that once had a reputation as a premier forensic science institutions.

In response to the inspector general's findings, agency officials reassigned three laboratory employees who worked on the Oklahom City case. They are David Williams, who supervised evidence collection; Roger Martz, head of the laboratory's chemistry unit, and James T. Thurman, chief of the laboratory's explosives unit.

Bureau officials, who acknowledge problems in handling evidence from the Oklahoma City bombing, said that no agent had been accused of deliberate wrongdoing. They said they did not expect that any mistakes would seriously undermine the Government's case, and they expressed confidence that there was sufficient evidence to convict the two defendants.

The officials said partial transcripts and summaries were in some cases incorrect and reflected exaggerated recollections of a few employees who were interviewed by investigators from the inspector general's office. The officials said some complaints raised by employees were investigated and dismissed in preparation of the report by the inspector general.

But the officials said some of the allegations appeared serious. For example, Mr. Williams, the chief laboratory examiner in Oklahoma City, was transferred from his job and was withdrawn as a prosecution witness in Oklahoma City. Mr. Williams had been responsible for conclusions about several major issues in the case, like the size of the bomb that tore the front off the Federal Building.

In one interview with the inspector general, he acknowledged that his opinion that the bomb contained 4,000 pounds of ammonium nitrate was an estimate based not on scientific studies but in part on searches of the defendants' houses.

Two laboratory workers said Mr. Williams had changed their dictated reports, in violation of F.B.I. policy. They said he made slight alterations in the wording of reports to eliminate uncertainties in the explosives evidence and making it easier for prosecutors to present the evidence as unequivocally consistent with the Government's theory of the case.