North Korea has obstructed the monitoring of foreign food aid and fuel oil assistance, according to two General Accounting Office reports to be released next week.

The reports suggest that the United States and foreign donors are having trouble detecting how much of their humanitarian assistance might be diverted to North Korea's military or government.

The GAO said power outages had affected monitoring equipment at the seven sites consuming fuel assistance. In Pyongyang, the capital, the monitoring system was "inoperative" for 46 percent of 1998, and in Chongjin it did not work at all. In April, monitoring equipment installed at the Pyongyang thermal power plant was destroyed by a fire.

In a separate report on food aid, GAO auditors complained that North Korea's failure to provide required reports meant that the United Nations World Food Program "cannot be sure that the food aid is being shipped, stored or used as planned."

Rep. Tony P. Hall (D-Ohio), who has visited North Korea, said there was "bias shot through" the GAO food report and charged that the investigators set out to "serve a partisan agenda" and undermine support for the food program. He complained that the GAO investigators never went to North Korea.

Both reports were done at the request of Rep. Benjamin A. Gilman (R-N.Y.), chairman of the House committee on international relations and a critic of Clinton administration policy toward North Korea.

Both aid programs are efforts by the Clinton administration to engage North Korea, alleviate widespread famine that is believed to exist there, and dissuade the Pyongyang government from pursuing the development of nuclear weapons and long-range missiles.

Half a million tons of food aid is being delivered to North Korea, according to the State Department, 80 percent of it through the U.N. World Food Program. The U.N. program is targeted at mothers, the elderly and infants.

"We have no evidence of significant diversion of food assistance to non-target populations," State Department spokesman James P. Rubin said yesterday. "Indeed there is ample evidence that U.S. food assistance to North Korea continues to reach those for whom it is intended."

The fuel oil assistance is part of the 1994 Agreed Framework. Under that agreement, the United States, South Korea and Japan formed a consortium to build two light-water nuclear power plants and deliver 500,000 tons of heavy fuel oil annually until the first reactor is completed. In return, North Korea froze operations at its other nuclear facilities, which were considered capable of producing materials for nuclear weapons.

"Naturally we want to ensure the best possible monitoring," Rubin said. "Given the opaqueness of North Korea, we're always looking for ways to improve."