A motion by Napster to have its court-imposed closure overturned has been denied by a federal appeals court judge.

The ruling by the 9th US Circuit Court of Appeals upholds District Judge Marilyn Hall Patel's order last year for the music file-swapping service to end operations until it could fully comply with an injunction to remove all copyrighted music.

Napster has not resumed its free service but has focused on setting up a fee-based online music operation.

The appeals court, which needed to demonstrate that Judge Patel committed legal errors, denied all of Napster's motions. Napster had argued that the ruling was vague and that the shutdown order was too harsh, among other things.

Judge Robert Beezer wrote in the appeals court decision: "We affirm both the modified preliminary injunction and the shutdown order. The shutdown order was a proper exercise of the district court's power."

The judge added that Napster must do everything feasible to block files from its system which contain noticed copyrighted works.

Napster has been battling with AOL Time Warner, Sony, Bertelsmann AG, EMI Group and Vivendi Universal for more than two years. In the meantime, Bertelsmann has become a major investor in Napster and is working to restart the service.

The Recording Industry Association of America, the trade group spearheading the lawsuit on behalf of the music labels, called the ruling a "strong endorsement" of its position on file blocking and praised the court's decision.

Napster made no immediate comment.