JUNEAU, Alaska (AP) _ Alaska on Tuesday sued Exxon Corp. and six other oil companies, alleging negligence for failing to prevent and clean up the nation's worst oil spill.

The lawsuit, filed in state Superior Court at Anchorage, does not specify the amount of damages sought for losses from the March 24 tanker disaster, which left nearly 11 million gallons of crude oil in Prince William Sound.

''If you assume that the damages haven't been half mitigated and then you add in any potential punitive damages, this is probably in the multiple billions,'' said Robert LeResche, the state oil-spill coordinator who announced the lawsuit at a news conference.

The lawsuit alleges that Exxon Corp. and Exxon Shipping Co., the subsidiary that owned the tanker Exxon Valdez, are responsible for the tanker running aground by failing to staff it adequately and supervise the crew properly.

The state also says Alyeska Pipeline Service Co., a consortium of oil companies that runs the trans-Alaska oil pipeline, failed to take prompt and adequate measures to contain and remove the spilled oil or prevent it from spreading into environmentally sensitive areas.

Alyeska was responsible for the initial response to the spill.

The lawsuit names Alyeska and each of the consortium companies: Exxon Pipeline Co., an Exxon Corp. subsidiary; Arco Pipeline Co.; BP Alaska Pipelines Inc.; Mobil Alaska Pipeline Co.; Amerada Hess Pipeline Corp.; Phillips Alaska Pipeline Corp.; and Unocal Pipeline Co.

Those companies controlled Alyeska's budget to a degree that makes them responsible for Alyeska's response to the spill, the lawsuit says.

''We feel that Alyeska as a corporation was merely a sham, a corporate shell if you will, behind which these partners have been hiding for the last 12 or 15 years,'' LeResche said.

The lawsuit also charges that the oil companies misrepresented their ability to contain and clean up oil spills, violated federal marine pilotage laws and inflicted ''severe emotional distress on Alaska residents.''

Exxon officials in Anchorage did not immediately return a phone call for comment.

The lawsuit seeks monetary damages for destruction of the environment and harm to the region's fisheries-based economy.

''The state recognizes that more than 1,000 square miles of its lands, waters and resources in or near Prince William Sound, the Kenai Peninsula and Kodiak Island suffered severe environmental damage, including the devastation of beaches and coastal waters, the death or injury of thousands of animals, the curtailment of important commercial fisheries, and the impairment of recreational opportunities,'' a state news release said.

The lawsuit also seeks punitive damages, its cleanup costs, its costs of studying and monitoring the spill, and a negligence fine under state law of up to $100 million. The state also asks for an injunction to ensure Exxon and Alyeska continue the cleanup until the environment is restored.

LeResche said he expected the lawsuit would take a decade to resolve.

In Alaska's report on the spill's cause to the National Transportation Safety Board, the state placed blame on ''arrogant and complacent people at the top levels of Exxon Shipping Co.''

''Exxon Shipping's failures and lapses in management were so numerous and pervasive that it is a wonder the Exxon Valdez was the first tanker grounded,'' LeResche concluded in the report last month.