Apple has used its last appearance at Macworld to announce a revamp of the iTunes music store, making almost its entire catalogue free of digital rights management (DRM) protection, and allowing iPhone users to download songs over a 3G connection.

The company said that iTunes users will now be able to download songs from Universal Music Group, Sony BMG, Warner Music Group and EMI, along with thousands of independent labels, in the 256Kbps iTunes Plus AAC format free from DRM.

Many have praised the move, but at least one company has declared itself unimpressed. "Downloads from iTunes are still in the AAC file format regardless of whether they are DRM-free," said Ben Drury, chief executive at music download site 7digital.

"The AAC file format is only compatible with iPods/iPhones and a limited number of other devices. So consumers who buy downloads from iTunes are still restricted to where they can play that music regardless of whether it's DRM free or not."

IPhone owners will now be able to download iTunes purchases over 3G connections, rather than over Wi-Fi or having to download tracks to a PC and then transfer them to the device.

"We are thrilled to be able to offer our iTunes customers DRM-free iTunes Plus songs in high-quality audio, and our iPhone 3G customers the ability to download music from iTunes anytime, anywhere over their 3G network at the same price as downloading to your computer or via Wi-Fi," said Apple chief executive Steve Jobs.

However, the addition of support for 3G could cause problems of its own. Fair use policies attached to most mobile data packages mean that the cost of downloading music over a 3G connection could end up a lot higher than just Apple's charge.

"2009 could be a pivotal year for rich mobile content, but for this to happen consumers need a transparent pricing mechanism to purchase rich content. Providers need to be sure that their consumers are treated fairly," said Andrew Bud, executive chairman at mobile transaction firm mBlox.

"The current hope that flat-rate data will be the total solution is fundamentally flawed, as market penetration is not high enough nor is it likely to be for some considerable time."

The pricing structure for music on iTunes will change in April with individual tracks being offered at one of three price points: 59p, 79p and 99p. Most albums will still be priced at £7.99.