Officials at Los Angeles International Airport could not account for more than 6,000 employe identification badges, or almost one in six, according to a source familiar with a General Accounting Office report to be released today.

The agency found "ineffective passenger screening and inadequate controls over personnel identification systems" at six major airports, including National Airport, according to a GAO statement that accompanies the report.

The study, conducted over the last 10 months, is being released less than two weeks after federal investigators found a gun and an airline employe identification badge in the wreckage of Pacific Southwest Airlines Flight 1771, which boarded passengers at the Los Angeles airport.

The flight carried David A. Burke, a former USAir ticket agent, and Raymond Thomson, the supervisor who had fired him for allegedly stealing $69 from in-flight liquor sales receipts. FBI agents believe that Burke shot Thomson and the plane's two pilots, causing a crash that killed all 43 on board. Before the identification badge was found, a USAir spokesman said the airline had confiscated and destroyed the former employe's badge.

The GAO report does not identify specific security risks at individual airports, but concluded that "in general . . . passenger screening process improvements are needed to ensure that the process effectively prevents firearms, explosives and other dangerous weapons from being carried on board an airplane and presenting a danger to the traveling public."

A House subcommittee asked GAO earlier this year to study security at 16 airports that require the tightest security because they screen more than 25 million passengers a year, serve more than 1 million international passengers or must cope with special threats.

The GAO report represents the first results, based on study of the Los Angeles airport, National, Chicago's O'Hare, New York's John F. Kennedy, Miami International and Atlanta's Hartsfield International airports.

The report is expected to be released today at a hearing of the House Committee on Government Operations' subcommittee on government activities and transportation.