SanDisk , which makes the Sansa - the second most popular MP3 player in the US - along with other flash memory products, is being accused of not paying for using MP3 codecs, which were invented by a coalition of companies, including Philips .

But SanDisk claims it does not need to pay royalties for these MP3 licenses because its products use completely unique technology.

"In a litigation currently pending in the Mannheim District Court," the company said, "SanDisk is showing that its MP3 players operate a technology which is completely different from a certain audio data transmission and reception technique that has been patented for Philips and others many years ago."

This has angered Italian firm Sisvel , which is charged with representing the owners of the MP3 patents. Sisvel says that SanDisk is knowingly infringing its clients' patents.

At the Internationale Funkausstellung ( IFA ) in September, Sisvel won an injunction against SanDisk which saw German Police seize all the products that SanDisk had on display.

A ruling is expected on this matter in March or April next year.