Several congressional leaders charged yesterday that the Pentagon has covered up critical findings of an internal report that identified major security breaches in some of the nation's most sensitive military programs.

More than a year ago, Congress asked for an investigation of security breaches, mostly at defense contractor facilities, and the Defense Investigative Service prepared the report. But the DIS report was rewritten and watered down by the Pentagon, legislators charged yesterday.

"The Defense Department report had gutted the most critical findings of its own investigators," House Armed Services Committee Chairman Les Aspin (D-Wis.) said in a statement. "When the Defense Department filed its report with Congress, the most graphic problems uncovered by the investigators went unmentioned."

A Defense Department official involved in the final report said yesterday the Pentagon gave Congress a revised version of the DIS study because officials believed some of the findings were exaggerated and "tainted by the personal bias" of the director of DIS. Pentagon officials also said the DIS report did not include enough of the improvements the department has made in its industrial security programs.

DIS found that some defense contractors were providing less security for their sensitive "special access" programs than for ordinary classified programs and said that some companies' security practices not only prevented lapses, but blocked investigators from detecting lapses, according to members of the House Armed Services Committee.

The report the Pentagon sent to Congress included 24 of the 26 recommendations made by the DIS "in whole or in part," according to James A. Hendrick, special assistant for oversight in the Pentagon's policy division. He said the Pentagon review panel added 16 of its own recommendations to the report.

"I'm not saying we don't have problems. We do," said Hendrick. "The problems we have in special access programs are no different than the MX or the B1 or any other major acquisitions program. A lot of times, in special access programs . . . they are solved a lot quicker because of national security implications."

Hendrick charged that "part of the early report was tainted by the personal bias" of the DIS Director Thomas J. O'Brien, who Hendrick said is engaged "in a power struggle . . . for more resources and people."

O'Brien, reported to be out of town, could not be reached for comment yesterday.

The Pentagon's special access programs, some of which are called "black" programs because their details and costs are kept secret, have been criticized by congressional oversight committees, which charge that the Pentagon needlessly classifies many programs to avoid public scrutiny of their costs.

Disclosures of security breaches involving a Lockheed Corp. employe working on the Advanced Technical Bomber, the "Stealth," prompted an investigation by the House Energy and Commerce oversight and investigations subcommittee last year.

The Armed Services Committee yesterday reported that the conclusions of the original DIS investigation, based on reviews of 101 top-secret programs at 607 contractor facilities, found 75 percent of the special access programs reviewed "could not supply documentation showing that they had ever been approved for such super-secret classification."

"DIS said it believed there were a 'significant number' of 'illegitimate' programs or programs unknown to those supposed to police contractors' special access operations," according to the committee statement.

The Pentagon's Hendrick said that finding was "completely wrong." He said that although there is no central department that oversees all programs, Pentagon officials responsible for specific projects "know where their programs are."