A Californian man has sued Apple for damages, claiming that he was forced to buy an iPod to play music he had bought online from the company.

Thomas Slattery filed his suit on Monday at the US District Court in San José and is seeking damages.

The crux of his case is based on the allegation that Apple's method of preventing iTunes music tracks being used on other players is anti-competitive and breaks antitrust laws.

The complaint further alleges that Apple is using its monopoly position to hamper competition in the digital music industry. It accuses Apple of turning an open standard into one that restricts choice.

The iPod and Apple's music download service dominate the digital music industry. Analyst group NPD reported in October that iTunes had a 70 per cent market share and that the iPod was the market leading music player.

At the end of last year Apple blocked a technology called Harmony that allowed music from RealNetworks' online store to be used on iPods. Apple described the company as having the "tactics and ethics of a hacker".

Apple declined to comment on the current lawsuit.