In a move sure to bruise Apple's ego, the bad boy gone good of the music download world, Napster, has launched the world's largest, and DRM-free, online music store.

More than six million tracks will be sold as MP3 files through the service, which will could quickly catch up with iTunes.

And the service already has the backing of all of the major music labels as well as indies.

Tunes will play on all MP3 players including iPods, and, because they are DRM-free, can even be burned onto CD or transferred from device to device.

Napster boss Chris Gorog says that the service, which offers songs for 99 cents (79p), has moved online music "from under the DRM cloud".

Napster previously only offered a monthly subscription service (which it is going to keep going) but Gorog added that the market seems to be moving towards "unlimited music models".

"It's great that we have finally gotten here", he said. "It is really the beginning of a level playing field, which I think is essential for Napster, but also for the health of the digital music business in general."