Digital music service Napster has launched an MP3 download store to challenge Apple's iTunes.

The new Napster store, carrying more than 6 million songs, will allow music fans to download tracks without copy protection or digital rights management (DRM), meaning MP3s can then be transferred to portable music players.

Napster chief executive Chris Gorog said: "We're now moving from under the DRM cloud. Now consumers can use Napster with any device."

Songs from the Napster library will be available for 99 cents each and $9.95 for an album.

Napster began as an illegal file sharing program that allowed users to download MP3s via a peer-to-peer network. After being shut down for copyright violations, the service continued by offering a paid-for streaming subscription package.

Apple's iTunes store currently accounts for more then 70% of digital music sales in the US.