The accidental destruction of microfilm seven years ago has handicapped Pentagon efforts to turn up records documenting President Bush's service in the Texas Air National Guard during part of 1972, a Defense Department public records official said in a letter to The Washington Post and other news organizations.

Records released to reporters on a CD-ROM this week essentially duplicate what the White House handed out in February regarding the president's Vietnam War-era service from 1968 to 1973. The records still do not provide evidence that Bush performed military service in Alabama, where he had been transferred in May 1972. Bush had sought the transfer to work on a Senate campaign.

Although the records gap was discussed at a White House news conference in February, details about why the records were missing were not known until the letter was sent by Pentagon Freedom of Information Officer C.Y. Talbott to news organizations.

"I am not able to provide complete copies of President Bush's payroll records for his National Guard service," Talbott said. He said this was because of "the inadvertent destruction of microfilm containing certain National Guard payroll records."

The records for "numerous service members" were damaged in 1996 and 1997 while officials tried to salvage deteriorating microfilm payroll records. The payroll summaries destroyed were for the first quarter of 1969 and the third quarter of 1972. "President Bush's payroll records for those two quarters were among the records destroyed," Talbott said.

-- James V. Grimaldi