Jones Day is acting for Apple Inc as the technology giant faces a class action law suit in the US amid claims that it violated antitrust law by not allowing music to be played on its iPod devices unless purchased through its iTunes store.

The class action, originally filed in 2010, is being brought by plaintiffs Melanie Wilson and Marianna Rosen.

They are represented by litigation specialist firm Robbins Geller Rudman & Dowd, which is acting on behalf "of all entities or persons who purchased certain iPod models between September 12, 2006 and March 31, 2009."

Jones Day is defending Apple in the suit, led by San Francisco based litigation partners Robert Mittelstaedt and David Kiernan.

The claim asserts that Apple aimed to strengthen its market "monopoly" by introducing unnecessary software updates to its devices shutting out their "rivals' competing audio downloads and portable digital media players by cutting off their access to the marketplace."

Customers were prevented from playing audio downloads purchased from competitors of iTunes on their iPods due to the company's Fairplay software. Furthermore, customers with non-iPod music players could not purchase their music from iTunes. The court filing also alleges that when competitors brought out products compatible with iPod or iTunes "Apple promptly issued software updates to end the compatibility."

Apple denies the allegations but admits selling music on iTunes "that was protected by Apple's proprietary digital rights management technology named FairPlay."

Wilson and Rosen are seeking $350m (