Military assistance during the 51-day siege of the Branch Davidian compound near Waco, Tex., in 1993 cost almost $1 million, and the military acted properly in providing it, the General Accounting Office has concluded in a report that it submitted to Congress.

The support included helicopters and other aircraft, tanks and other combat vehicles, a wide variety of equipment and training of the federal agents who were conducting the siege, the report said.

The GAO, an investigative arm of Congress, did not explore whether military personnel played any role in the April 19, 1993, assault on the compound. Military documents show that three members of Delta Force watched the tank and tear gas assault, which ended when the compound burst into flames, killing 76 people.

Any direct military involvement in a civilian law enforcement operation would have required a presidential waiver of the law barring such activity. But military officials insist that the military personnel on the scene were only observers.

Under federal law, the military can assist civilian law enforcement agencies in certain circumstances, including operations targeted on suspected drug activity. In seeking military help for their initial, unsuccessful attempt to arrest Branch Davidian leader David Koresh, the Bureau of Alcohol, Tobacco and Firearms (ATF) said it suspected that the cult's compound was also the site of a clandestine methamphetamine laboratory. It was on that basis that two requests for help were approved by the Texas National Guard and Operation Alliance, a clearinghouse that represents counterdrug interests of federal, state and local law enforcement agencies.

A report on the 1995 House hearings on the Waco incident said ATF officials deceived the military to obtain assistance "under the guise of a counternarcotics operation." The report questioned the credibility of drug allegations against Koresh, terming them "very stale by legal standards," and said the sect's previous leader, not Koresh, was suspected of methamphetamine manufacturing.

"ATF agents misrepresented to Defense Department officials that the Branch Davidians were involved in illegal drug manufacturing," the congressional report said. "As a result of this deception, the ATF was able to obtain some training from [military] forces which would not have otherwise provided it."

The GAO reached an opposite conclusion. It said the law sets no standard for deciding what types of counterdrug activity qualify for military support and that military officials "have considerable discretion" in making such decisions.

"We found no basis to conclude that the officials involved abused that discretion," the GAO report said. "We also found no indication that ATF officials misrepresented the information provided to the military in order to obtain the support. Therefore, we conclude that the military's decision to approve the counterdrug support was reasonable and authorized under the relevant statutes."

Once the 51-day standoff began, according to the report, it was no longer necessary to have a connection to counterdrug activities because that "qualified as military assistance to civilian authorities."

Most of the military assistance costs--totaling $982,400--were incurred by the Texas National Guard and active Army units, the GAO report said. The FBI and the ATF have reimbursed the military for $747,300, most of which was paid by the FBI.

The GAO also provided a detailed accounting of how the money was spent, including $98,264 in undercharges and $539 in overcharges by the military. It said, for example, that the Army did not bill civilian agencies for the loss of two night vision goggles, at a cost of $9,168. It said the Texas National Guard overcharged civilian agencies $41 for vehicle parts.

Staff writer Richard Leiby contributed to this report.