The long-anticipated MP3 service has finally arrived, although the online retailer's download store had a low-key launch.

The service went live today (Dec. 3) and boasts 3 million DRM-free tracks from all four majors and leading independent labels, through licensing deals with the Orchard and IODA. Indie label groups Beggars and Concord have also signed up to the service.

Prices undercut iTunes, with tracks starting at 59 pence (87 cents) and albums priced from £3 ($4.43). The standard iTunes price of a track in the U.K. is 79 pence ($1.17).

Albums available for £3 include chart titles such as Take That's "The Circus" (Polydor) and Kings Of Leon’s "Only By The Night" (Hand Me Down/RCA), as well as back catalog such as Led Zeppelin's "IV" (Atlantic) and Joni Mitchell’s "Blue" (Warner Bros).

Despite the lack of any real fanfare for the launch, the service appears to be complete and resembles the U.S. version. The MP3 site recommends installing the 'Amazon MP3 Downloader' software, otherwise full album purchases will not be possible.

"We're excited to provide our U.K. customers with more ways to discover and enjoy great music," said Greg Greeley, VP of Amazon EU Retail, in a statement. "In addition to the millions of low-priced CDs available in our music store, Amazon MP3 now provides a vast selection of DRM-free albums and songs across every genre you can think of, ready to enjoy in seconds."

Ged Doherty, chairman and CEO of Sony BMG Music Entertainment U.K., added: "Amazon's music services in the U.S. have attracted new digital music consumers and helped grow the digital market. We have high hopes that it will have the same impact in the U.K. Amazon are an excellent and well trusted retailer, this new store can only be good for U.K. music."

However, the arrival of MP3s on does not mean MySpace will immediately sell downloads in the U.K. While powers MySpace MP3 sales in the U.S., a spokesman for MySpace told there was no confirmed date for when the social network site would start selling downloads in the U.K.’s tracks are encoded at 256 kbps and will work on PC and Mac as well as any music device.

Rival download store 7digital's CEO Ben Drury responded to the launch today by suggesting that Amazon's arrival in the U.K. download market was "a little late" and commented that its tracks were not of the same quality as 7digital's 320kbsp MP3s.

However, Drury added in the statement: "Amazon's entry into the market is good news for the digital music consumer and will help accelerate the migration from physical format to digital. This is another victory for MP3 and another blow for iTunes." The majority of iTunes tracks feature digital rights management.

The launch follows online retailer's roll-out of its DRM-free service PlayDigital with all majors on board in October, while 7digital went fully MP3 in September.