Coast Guard Commandant Paul Yost reviewed an Exxon Corp. proposal Saturday to clean up the nation's worst oil spill and threatened to "kick rear ends" until the job was done.

But environmentalists said the oil was spreading Saturday to waters near the key fishing port of Kodiak, and some grimly predicted it would wipe out the sea otter population in Prince William Sound, where the tanker Exxon Valdez ran aground on a reef March 24.At least 10.1 million gallons of Alaska crude oil spilled into the sound from the accident and another 1 million gallons was lost when the rest of the ship's cargo of 53 million gallons of oil was transferred onto three other tankers.

Yost was appointed by President Bush a week ago to oversee the cleanup operation, and he imposed a Saturday night deadline on Exxon to come up with a plan of action.

Officials said Exxon beat the deadline, giving Yost a preview of the plan late Friday. Yost was studying the proposal Saturday with officials from Exxon and the state. Details of the plan were not made public.

"I'm not happy with what's happened here in the last 22 days, and I don't think the president is either," Yost told a meeting of scientists Friday night. "I consider this a war with the spill," he said. "I'm here to clean it up and direct Exxon in the cleanup."

Yost declined to say what he would - or could - do if Exxon failed to come up with an acceptable proposal, but he said, "I'm kicking rear ends and taking some names."

The cleanup took on new urgency during the weekend because of predictions that thousands of sea otters were in danger from the spreading oil slick and warnings that the oil was heading toward critical wildlife habitats and valuable fishing grounds.