Despite assurances by then-Defense Secretary Caspar Weinberger that there were few problems, 90 percent of the defense contractors surveyed in a Pentagon study last year were found to be sloppy in handling secrets.

The study was done by the Defense Investigative Service but was withheld from Congress by Weinberger because he didn't like the conclusions of the report, according to sources who spoke Monday on condition they not be named.The report dealt with the way Pentagon contractors handle highly classified information known as "special access programs."

It was ordered by Congress in 1986 after an investigation by a House subcommitee into allegations that Lockheed, a major defense contractor, couldn't find a number of classified documents on its highly secret "stealth" airplane program.

The DIS study was not directly related to the current criminal investigation of the Pentagon and defense contractors. That probe centers on allegations that defense contractors and consultants, many of them former military men, bribed Pentagon officials for information that could be vital in winning contracts worth billions of dollars.

The DIS review of hundreds of contractors contradicts a statement by Weinberger to Congress that "the vast majority" of defense contractors did a satisfactory job of handling classified material.

The 80-page DIS report is classified and has not been publicly released. But its contents were described Monday by sources who had access to the document.

The study reviewed 101 different programs at 603 contractor locations around the nation, the sources said. Many of the facilities were working on more than one classified Pentagon program.

The study found that only 10 percent of the contractors had no deficiencies, the sources said.

Six percent were rated unsatisfactory, 47 percent had major deficiencies, 34 percent had "letter of requirement" deficiencies, and 3 percent had problems that were corrected on the spot, according to the sources.