The Federal Bureau of Investigation and the Labor Department are investigating allegations that a senior official in the Philadelphia office of the Occupational Safety and Health Administration accepted bribes from a union official in exchange for targeting OSHA inspections at nonunion rather than union construction projects, according to sources.

"It has come to our attention that an ongoing investigation is under way involving certain aspects of the operations of our Philadelphia area office," an OSHA statement yesterday said. "Upon completion of the investigation and receipt of the result, the agency will determine what, if any, appropriate actions may be necessary."

OSHA, which earlier this month announced an internal investigation of its New York City area office and the temporary transfer of its two top officials, said yesterday it has temporarily transferred its Philadelphia area director, Bernard Dillon.

An agency spokesman said the transfer "is not a disciplinary action" and may be reconsidered when the investigation is completed. Dillon was not available for comment.

Sources said the probe began late last year after an unidentified official of a Philadelphia roofers' union approached nonunion building contractors, seeking work for union members. The union official said that if companies agreed to sign union contracts, the official could guarantee that OSHA would not inspect the job sites, but instead would target its inspections on nonunion competitors, the sources said.

The FBI, according to the sources, obtained videotaped evidence of at least one top OSHA official accepting money and discussing agency inspection plans in the construction industry, OSHA's most active area of safety inspection. The case against the official, which is being handled by the U.S. attorney's office in Philadelphia, has not yet been presented to a grand jury, the sources said.

OSHA earlier this month temporarily removed its two top New York area officials pending an internal investigation of the agency's failure for four years to correct serious health violations at two factories producing mercury.

Depending on the outcome of the Philadelphia case, "this is another black eye that Labor Secretary William E. Brock doesn't want for OSHA," an agency official said.

Brock has identified OSHA as a prime area of concern because the agency has been without a director for six months and has been criticized by business and labor. Brock submitted the name of John Pendergrass, a corporate safety expert, to head OSHA, but the White House has not yet nominated him. Staff writer Howard Kurtz contributed to this report.