Apple's success in transforming its iPod into the market-leading music player appears to have undermined some CD protection technologies based on Microsoft software.

Last month Velvet Revolver album 'Contraband' hit number one in the US charts - despite the fact it used copy protection and wouldn't play on an iPod.

Cnet reports that the two companies behind the most-used copy protection technologies are "scrambling to create new versions of their technologies that are compatible with Apple's popular digital music player". And their efforts could "ultimately be a setback to recent Microsoft strides into the music business".

SunnComm CEO Peter Jacobs told Cnet that "80 per cent" of the customer comments his company receives relate to the lack of iPod compatibility.

After years of work, existing copy-protection technologies seemingly manifest themselves as CDs containing audio tracks that cannot be ripped by a computer, along with digital tracks that can be transferred - using Windows Media Audio.

That move appeared to give Microsoft an advantage in the business, but Apple's success has "forced a change in plans".

The report claims: "SunnComm and Macrovision each say that the new generations of their technology, due later this summer and early next year, respectively, will let people effortlessly create versions of songs for computers and portable players," for iPods and other devices.

This compatibility is critical, an analyst said, observing that if people stop buying particular albums because they will not work with an iPod, then the labels won't like it.