Apple has hinted for the first time that it will open up its iTunes music store to be compatible with other players such as Microsoft's Zune and Sony's Walkman phones if the music industry drops its insistence on making sure music files are locked with copyright protection software.

In an open letter on the company's website, Apple's CEO Steve Jobs criticises Universal, Sony BMG, Warner and EMI for holding back the industry insisting "DRMs [Digital Rights Management] haven’t worked, and may never work, to halt music piracy".

Jobs goes on to question why "if the music companies are selling over 90 per cent of their music DRM-free, what benefits do they get from selling the remaining small percentage of their music encumbered with a DRM system?".

In his letter, Steve Jobs offers three alternatives to the current problem; Continue as is, Apple to licence its FairPlay technology, or to abolish DRM completely.

"In such a world, any player can play music purchased from any store, and any store can sell music which is playable on all players."

Earlier this week Apple iTunes store users experienced problems with Windows Vista over DRM copyright issues. Although Apple has since released a patch for the problem, it has encouraged users to wait until a new version of iTunes is released in a couple of weeks.