Sainsbury's is the latest retailer to offer an unlimited music-download service.

Subscriptions to the Datz Music Lounge service, which includes a software CD and a USB dongle that must be attached to a PC for downloads to take place, will be available through the supermarket. For £99 a year, users can download as many songs as they like and will be allowed to keep the tracks, which are DRM-free, once the year is up.

Datz, which is similar to Nokia's Comes with Music service but doesn't need a handset, offers in the region of two million tracks from independent labels as well as EMI and Warner. While initially the files can only be downloaded onto a Windows-based PC, they can be moved to any device which supports MP3s.

It is also thought the service will be made available through a high-street phone retailer in the future.