Michael Jackson
King of Pop Michael Jackson died June 25, 2009. The circumstances of the 50-year-old singer's death form the subject matter of an involuntary-manslaughter trial under way in Los Angeles. Reuters

Apparently hackers have returned to plague Sony. This time, in what is certainly one of the most high-profile hacks on Sony's networks in recent times, a number of unreleased songs and musical material belonging to the late Michael Jackson, has been hacked and stolen.

The Sun quotes Sony as saying "some of the most important recordings in history" were the ones hacked. More than 50,000 music files (worth £160m) have reportedly been illegally downloaded and stolen.

Jackson's estate signed the biggest recording deal in history, worth £164m ($250m) with the company in 2010, giving it the rights to sell his whole back catalogue as well as previously unreleased tracks, a report in The Guardian stated.

Jackson's back catalogue included unreleased duets with artists from Freddie Mercury to Black Eyed Peas singer Will.i.am, according to The Sun.

Reports suggest two unidentified persons were arrested in connection with this matter but were later released on bail.

Jackson died in June, 2009, at the age of 51.

This is not the first time Sony's online networks have been breached. In what proved to be a headache for the Japanese company, hackers stole more personal details of about 70 million users of the Sony PlayStation Network.