Sony Corp bosses are working on a top secret deal to sell off their music publishing arm, which is the part of the company that houses the rights to most of the Beatles' songs.

The Wall Street Journal has obtained a leaked internal email, which discusses the possibility of selling off the unit Sony owns jointly with the estate of the late Michael Jackson.

The publication estimates the package is worth almost $2 billion (£625 million), but the leaked correspondence does not mention a price.

The potential sale was being handled by Sony Entertainment Chief Executive Officer Michael Lynton among others, according to the 21 November (14) email penned by Chief Financial Officer Steve Kober, who seemed quite surprised about a fellow executive's knowledge of the deal.

He wrote, "We are very surprised that the attached listing includes the comment about the sale of Sony/Atv (Music Publishing). As you know quite well, this is a top-secret project."

The email leak is the latest following a security breach of Sony's database last month (Nov14). Activists calling themselves Guardians of Peace hacked into the media giant's systems as part of a cyberterrorism threat to leak vital documents if the company's bosses continues to promote Seth Rogen comedy The Interview, which involves a plot to kill North Korean leader Kim Jong Un.

Fbi agents have tied the hackers to North Korea.