Sony BMG Music Entertainment, the last major music label holding out against selling music online without copy protection, relented Thursday and announced Amazon.com Inc.'s digital music store will carry songs by its artists.

Until this week, Sony BMG had resisted selling songs from its catalog without embedding digital rights management, a generic term that refers to special encoding which prevents music files from being endlessly copied.

Amazon's digital music store sells songs only in the MP3 format, which can be burned onto CDs, copied to multiple PCs and played on any number of digital media players, including Apple Inc.'s iPod and Microsoft Corp.'s Zune.

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Sony BMG, which is jointly owned by Sony Corp. and Bertelsmann AG, said Tuesday that it also plans to sell some DRM-free music directly to customers in the U.S. and Canada.

Platinum MusicPass, as Sony's system is called, will start Jan. 15 with 37 titles.

To use it, shoppers must buy a $12.99 card in person at a store — Best Buy, Target and other retailers will sell them — and then log on and download music.

Sony BMG artists will begin showing up on Amazon's MP3 store later in January. The label's artists include Jennifer Lopez, Britney Spears and Bob Dylan.

Universal Music Group, EMI Music Group PLC and Warner Music Group had already agreed to sell large portions of their catalogs on Amazon, as had thousands of independent labels.

Most of the 3.1 million available songs cost 89 cents to 99 cents each and most albums sell for $5.99 to $9.99.