Victor Stello Jr., a senior Energy Department official, made false or misleading statements to Congress and to investigators at the Nuclear Regulatory Commission and could face prosecution, according to a report by the NRC's inspector general.

After a six-month inquiry, Inspector General David C. Williams reconfirmed the findings of previous investigations that Stello mishandled an investigation into allegations of safety problems at a nuclear power plant in New York. In testifying before congressional committees about that affair, Williams found, Stello made statements "contradictory to the facts of the case."

In his private report to NRC commissioners, first reported in The New York Times, Williams said he gave his findings to the Justice Department for possible prosecution.

Stello was formerly the NRC's executive director of operations. President Bush nominated him to be assistant energy secretary for defense programs, but Stello failed to win Senate confirmation, largely because of questions about the case reviewed in the report. He withdrew his name in April, after Energy Secretary James D. Watkins and Senate Armed Services Committee members were told of Williams's findings.

Watkins then named Stello a deputy assistant secretary, a post that needs no confirmation, and put him in charge of restarting operations at several of the department's troubled nuclear weapons assembly plants.

A spokesman for Watkins said yesterday that Stello "continues to have Watkins's full support." He said Stello "has been doing an outstanding job" and there was no reason to disrupt his work because of a new airing of old issues.

Stello has declined to comment to reporters on his handling of the so-called "Fortuna affair," a complicated NRC internal investigation that involved everything from allegations of sexual harassment to reports of nuclear power plant operators using drugs while working.