Apple is investigating allegations that it misled people over the battery life of its iPod digital music player.
The iPod has been a major hit with music-lovers
Five separate class actions were filed against the company in December 2003.
Complaints that the iPod's battery did not last as long as Apple said and degraded over time came to the surface when the latest model went on sale.
The iPod has dominated the digital music player market, with over two million of the white gadgets sold worldwide since its release.
In its quarterly financial report to the US Securities and Exchange, Apple said it had been named in the class action suits and that it would be looking into the claims alleging "misrepresentations by the company relative to iPod battery life".
The allegations detailed in the legal action, under the names Chin, Keegan, Hughes, Westly and Craft, include unfair competition and claims of false advertising, fraudulent concealment and breach of warranty, Apple says.
The legal action claims false advertising
The lawsuits say Apple's claims about the built-in battery have violated California's competition laws, and that it has breached the state's Consumer Legal Remedies Act.
Since the end of last year, Apple has offered an extended warranty scheme which covers iPod owners for an extra year.
It has also provided a battery replacement for affected iPods, at an extra cost to consumers.