San Francisco  - A federal appeals court on Monday ordered Exxon Mobil Corporation to pay victims of the 1989 Exxon Valdez oil spill 480 million dollars more in interest on their delayed punitive damage awards.

The decision by a three-judge panel of the US 9th Circuit Court of Appeals more than doubles the oil giant's costs in settling the lawsuits brought by fishermen, cannery workers, marine services and eco-tourism purveyors whose livelihoods were ruined by the devastating oil spill.

The court said that it arrived at the figure by calculating a 5.9- per-cent interest charge on the original damages of 5 billion dollars imposed by an Alaskan jury in 1996. That amount was eventually reduced to 507 million dollars by the US Supreme Court last year.

Exxon, the world's largest publicly traded company, insisted that the interest should accrue only from the date of the Supreme Court ruling. A company spokesman said Exxon would study Monday's ruling before deciding whether to appeal. (dpa)