Allied attacks on Iraqi positions are believed responsible for up to 30 percent of the oil spilled in the Persian Gulf, and there is much less oil than initially feared, Saudi officials say.

The Saudi government had initially estimated that the oil amounted to about 460 million gallons, which would have made it the world's largest spill.Latest estimates based on satellite photography, however, indicate that 65 million gallons of crude have entered gulf waters since the war began Jan. 17, said Abdullah Dabbagh, of the University of Petroleum and Minerals.

Dabbagh told a conference on the Saudi economy that sea beds and plankton fields shown in satellite imagery of the gulf's shallow waters appeared to have been mistaken for oil.

He described the initial figure of 460 million gallons as an estimate of how much oil could have entered the water, not an "approved scientific study" of the actual amount.

"It was a worst-case scenario," he said. "After an investigation, we scaled down the size."

Dabbagh said he hoped confusion about the slick, its size and sources would not overshadow the great harm it had done. It is still five times larger than the 1989 Exxon Valdez spill in Alaska.

Officials of the Saudi environmental agency said Tuesday they believed 20 percent to 30 percent of the oil resulted from allied attacks on Iraqi land and naval targets along the Kuwaiti coast.

About 70 percent of the oil is believed to be the result of Iraqi soldiers having opened valves at a Kuwaiti terminal, according to a ranking official at the Meteorological and Environmental Protection Agency who spoke on condition of anonymity.

The oil has damaged more than 100 miles of Saudi coast, including pristine beaches, fertile sea beds, important bird nesting areas and rich tidal pools.

The slick has killed thousands of birds, including cormorants, grebes and rare flamingos and herons.

For several days, it shut down one Saudi desalination plant that provides drinking water.