Warner Music, the record company behind Led Zeppelin and James Blunt, dropped its long-standing opposition to releasing digital music without copy protection yesterday, as it made its entire catalogue available to the United States download site of Amazon.com.

The U-turn - following similar decisions made by EMI in the spring and Universal in the autumn - means that in less than a year the music industry has abandoned copy protection and is selling digital music that, in theory, anybody can share freely with others.

Eleven months ago Edgar Bronfman, the chief executive of Warner Music, said that proposals by Steve Jobs, the chief executive of Apple, to drop copy protection were “without logic or merit” and noted that his company would not “abandon” the traditional system. However, Warner Music now believes that it has little choice but to follow its competitors.

The company is keen to work with Amazon, which is selling music using the open MP3 standard, in the hope that the online retailer can help to boost a digital market that is not growing fast enough to offset a 15 per cent decline in physical album sales in the US.

By dropping copy protection, music companies are making it simple for consumers to buy songs online and load them on to any digital music player. The copying of music remains illegal, but it is harder to enforce in an industry in which piracy is rampant. Warner Music’s agreements with Amazon cover the US, but they are expected to extend internationally soon.

Warner Music is also in discussions with Apple about releasing unprotected versions of its songs via iTunes. Only EMI has signed up with Apple, with Universal Music, the market leader, preferring to work with other digital retailers, such as Amazon, to enhance its competitive position.

Sony BMG, the No 2 company, is the only major that is refusing to join in, although it has indicated privately that it believes it has little choice but to fall in line with its peers.

However, even Warner Music concedes that it is not clear whether the decision of rivals to abandon copy protection has boosted the sales of its competitors or increased the volume of piracy.

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