Fresh privacy fears have been sparked after it emerged that Apple has embedded personal details into music files bought from its iTunes music store.

Technology websites examining iTunes products discovered that personal data, including the names and e-mail addresses of purchasers, are inserted into the AAC files that Apple uses to distribute music tracks.

The information is also included in tracks sold under Apple’s iTunes Plus system, launched this week, where users pay a premium for music that is free from the controversial digital rights management (DRM) intended to protect against piracy.

The Electronic Freedom Foundation, the online consumer rights group, added that it had identified a large amount of additional unaccounted-for information in iTunes files.

The foundation said it was possible that the data could be used to “watermark” tracks so that the original purchaser could be tracked down if a track appeared on a file-sharing network, although experts said that it would be relatively easy to “spoof” such data.

Ars Technica, one of the first websites to unveil the hidden information, said: “Everyone should be aware that while DRM-free files may lift a lot of restrictions on our personal usage habits, it doesn’t mean we can just start sharing the love, so to speak. Sharer beware.”

An Apple spokeswoman was unable to comment.

The discovery of the data, of which most iTunes users will have been unaware, underscores the reluctance of music groups to allow music to circulate freely over the web.

With estimates suggesting that 40 tracks are digitally boot-legged for every legally down-loaded track, piracy remains a massive problem for the industry and music groups have largely proven reluctant to withdraw the controversial DRM technologies.

Apple had sought to present itself as a consumer champion, with the group’s chief executive, Steve Jobs, insisting earlier this year that his company would drop DRM “in a heartbeat” if allowed to by the labels.

Previously, Apple’s DRM system had been criticised by European regulators for being anticompetitive because it allowed tracks to be played only on Apple’s iPod music players.

Apple’s iTunes Plus service offers DRM-free music of a higher quality than standard iTunes tracks for 99p a song, compared with 79p for a standard track. Users who opt to pay extra for iTunes Plus tracks will be able to play the music without limitations on the type of music player or number of computers that purchased songs can be played on.

The discovery comes amid fears of a creeping culture of consumer surveillance by technology companies. Google also gave rise to fears yesterday when it unveiled thousands of street-level photographs of major American cities as part of its online maps service. Within hours, bloggers picked out images of people, their faces visible, being arrested, sunbathing and urinating in public.

Times Recommends

• Lies and cover-up at MG Rover exposed by report
• High oil prices push manufacturing costs up
• Primark founder steps down as chief executive