Apple has made its first move to thwart music pirates who have been using iTune's built-in music sharing features to steal music.

The company last night released iTunes 4.0.1 for OS X. This 8.2MB update offers a "number of performance and network access enhancements". It also prevents file sharing between Macs using iTunes 4.0.1 over the Internet. Mac users can only share over local networks on the same subnet.

Speaking to MacCentral last night, Apple revealed that over three million songs have been purchased and downloaded through its iTunes Music Store so far.

It added that the copyright protection developed to secure purchases made through the store has not been breached: "Music purchased from the iTunes Music Store can only be played on up to three authorized Macs, and there has been no breach of this security."

The iTunes update follows the appearance of non-approved programs capable of harnessing iTunes and the Internet in order to steal music from other users, a feature Apple does not support.