A federal judge in Anchorage ordered Exxon Mobil Corp. on Wednesday to pay $6.75 billion in punitive damages and interest to thousands of fishermen and others affected by the 1989 Exxon Valdez oil spill.

"We have now closed the trial court doors for the last time in this litigation after 15 years," said David Oesting, lead attorney for the plaintiffs. "We're definitely on track to the end of the entire dispute."

In Wednesday's ruling, U.S. District Judge Russel Holland ordered Exxon Mobil to pay $4.5 billion in punitive damages and about $2.25 billion in interest.

The money is to go to 32,000 fishermen, Alaska Natives, landowners, small businessmen and municipalities affected by the nearly 11 million gallon spill in Prince William Sound.

An Exxon Mobil official said the Irving, Texas-based company plans to appeal the 81-page ruling, the latest of several issued by Holland.

The 9th U.S. Circuit Court of Appeals has twice vacated Holland's decisions in the case, said Exxon spokesman Tom Cirigliano. Holland had been ordered by the appellate court to reconsider his findings of damages.

"This ruling flies in the face of the guidelines set by the appeals court," Cirigliano said of Wednesday's order.

In 2002, Holland reduced the Exxon punitive damages award to $4 billion after a three-judge panel sent the original $5 billion verdict back, saying it was excessive.

In his latest ruling, the judge was to consider a U.S. Supreme Court decision last year involving a Utah traffic accident and damages awarded in that case.

Attorneys from both sides argued that the Supreme Court case, State Farm Mutual Automobile Insurance Co. v. Campbell, supported their damages claims. In that case, the Supreme Court ruled that a state court jury's award of $145 million to punish the insurance company was grossly excessive when actual damages were $1 million.

The high court held that the ratio of punitive to actual damages should not exceed single digits, or 9-to-1.

Exxon attorneys argued that injury to plaintiffs was only economic and damages should be based on a lower ratio, such as 1-to-1 or less. That would produce punitive damages of about $25 million. Exxon has already paid $3.2 billion on cleanup, settlements and other fees and penalties, attorneys said.

But lawyers for the plaintiffs argued that the key issue is conduct, and that Exxon's was among the worst. They said Exxon knew that tanker Capt. Joe Hazelwood had a drinking problem but still allowed him to take charge of the Exxon Valdez. They calculated actual damages at more than $500 million and punitive damages at roughly $5 billion based on a 9-1 ratio.

Cirigliano said that when the matter was sent back to Holland, Exxon Mobil lawyers predicted this would be the result -- "serious further delays" -- from having to appeal rulings from a court "that has already made numerous mistakes."

The spill occurred March 24, 1989, less than three hours after the 987-foot ship left the Alyeska Pipeline terminal in Valdez.

The ship grounded at Bligh Reef, rupturing eight of its 11 cargo tanks and spewing some 10.8 million gallons of crude oil into the sound.

An estimated 250,000 seabirds and thousands of marine mammals died as a result of the spill, which contaminated more than 1,200 miles of shoreline.

Lingering effects of the spill include declines and stunted growth in various marine populations and indirect mortality increases in pink salmon populations.