Sony Music, a unit of Sony Corps, signed a deal with Jackson's estate in 2010, the year after the "Thriller" singer's death, to release 10 albums covering previously unreleased material and his back catalogue.

The value of the agreement was widely reported to be around $250 million, making it one of the biggest in music history. But sources close to the label have disputed the figure, calling it pure speculation on the part of the press.

On Friday, two men appeared in a British court accused of offences connected with the alleged security breach. They were arrested last May and charged in September.

James Marks and James McCormick denied the charges under the Computer Misuse Act and the Copyright, Designs and Patents Act at Leicester Crown Court.

According to the Serious Organized Crime Agency, they were remanded on bail and were due to stand trial in January next year.

Sony Music issued a brief statement:

"We confirmed the breach last May and immediately took steps to secure the site and notify authorities," the company said. "As a result, the two suspects were arrested. There was no consumer data involved in the incident."

The IFPI record industry lobby group declined to comment on the ongoing investigation.

Sources could not confirm British media reports that tens of thousands of files, most of them by Jackson, were allegedly downloaded illegally, although files can vary from entire tracks to small snippets of music.

The allegations come less than a year after Sony faced widespread criticism over its systems security when hackers accessed personal information on 77 million PlayStation Network and Qriocity accounts.

The company later revealed hackers had stolen data from 25 million accounts of a separate system, its Sony Online Entertainment PC games network.

Industry sources said there was nothing to suggest that the large-scale hacking cases were linked to the Jackson files breach.

(Reporting by Mike Collett-White, editing by Paul Casciato)

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