A federal court ruled Monday that Exxon Mobil Corp. owes $507.5 million, plus 5.9% annual interest accrued since 1996, in punitive damages to plaintiffs affected by the Exxon Valdez oil spill.

A federal court ruled Monday that Exxon Mobil Corp. owes $507.5 million, plus 5.9% annual interest accrued since 1996, in punitive damages to plaintiffs affected by the Exxon Valdez oil spill.

In a divided opinion, the U.S. Court of Appeals for the Ninth Circuit determined that the Irving, Texas-based company and the plaintiffs would have to pay for their own legal costs and court fees. Exxon’s legal fees approach $70 million, according to court filings.

The ruling follows a decision by the U.S. Supreme Court last year to limit the punitive damages awarded the commercial fishermen and other plaintiffs who sued Exxon over the Valdez spill to about a tenth of the $5 billion awarded by a jury in September 1996. Interest payments, however, amount to hundreds of millions of dollars, according to the latest opinion. The company has already paid plaintiffs about $383.4 million, a spokesman said.

ExxonMobil, the world’s largest publicly-traded oil company, insisted that the interest should run from the 2008 date of the Supreme Court decision. The company also wanted the plaintiffs to pay for at least 90% of the litigation costs.

An Exxon spokesman said that the company “will review the opinion before commenting further.”

A lawyer for the plaintiffs couldn’t be reached.

The opinion brings the legal saga spawned by the 1989 Exxon Valdez oil spill closer to an end.