Entertainment giant Sony has confirmed that hackers accessed its systems and compromised Michael Jackson’s entire back catalogue, including many unreleased songs.

The hackers managed to get their hands on 50,000 songs, most of which were by the late pop legend and some of which had never been released before. A report in the Daily Mail added that works by Jimi Hendrix, Paul Simon, the Foo Fighters and Avril Lavigne were also compromised during the attack.

Sony signed a $250m record deal with Jackson’s estate back in 2010, nine months after his death. The deal, said to be the biggest record deal ever signed, gave Sony the right to sell and distribute his back catalogue.

It is thought that the hack occurred around the same time Sony’s PlayStation Network (PSN) was hacked in April 2011 but was not noticed at the time. It is thought that the breach was only noticed through monitoring of social networks and Michael Jackson fan sites.

"Everything Sony purchased from the Michael Jackson estate was compromised," a source told the Sunday Times. "It caused them to check their systems and they found the breach. There was a degree of sophistication. Sony identified the weakness and plugged the gap."

Two men arrested last May in the UK over the hack appeared in court last week, according to the Guardian. James Marks, 26, and James McCormick, 25, both denied the charges under the Computer Misuse Act and the Copyright, Designs and Patents Act and were bailed. They are due to stand trial next January.

Last April it was revealed that hackers had accessed Sony’s networks on a number of occasions. The personal details, including names, email addresses and, possibly, credit card information, of 77 million PSN users were compromised.