Australian-born media mogul Rupert Murdoch has abandoned a $38 billion plan to combine Fox Corporation and News Corporation, a bold move that would have reunited his broadcasting and print empires.

According to a regulatory filing in the US that emerged on Wednesday (Australian time), Mr Murdoch had determined that a combination of the companies was “not optimal” for shareholders.

The decision was also revealed in near identical releases from News Corp and Fox on Wednesday.

The deal would have reunited the media empire that Mr Murdoch split nearly a decade ago, after years of expanding his global media empire. The combined companies would have had about $38 billion in revenue.

The official reason at the time for the plan, according to one insider, was that it would generate more value for shareholders.

The reunification bid came two years after Fox sold the bulk of its film and television assets to Walt Disney Co for $US71 billion ($A113 billion).

It still operates the right-wing channel Fox News, as well as Fox Sports and Fox TV Stations. News Corp owns The Wall Street Journal, New York Post, HarperCollins, among a string of other assets.

There were no offers exchanged between News and Fox before talks were abandoned, sources familiar with the process said this week. They also said pushback from News Corp shareholders played a role in the plans being scrapped.

Mr Murdoch proposed reuniting his media empire late last year, arguing that together the publishing and entertainment companies he split in 2013 would give the combined company greater scale in news, live sports and information, sources said on Tuesday.

Several people close to the Murdochs viewed the effort to reunite the media companies as driven by the 91-year-old Mr Murdoch’s succession planning to consolidate power behind his oldest son, a notion the company described as “absurd” in November.

Some of News Corp’s larger shareholders, including Independent Franchise Partners and T Rowe Price, baulked at the idea.

In a letter to News Corp employees on Tuesday, News Corp chief executive Robert Thomson said: “In my note to you in October, I said the special committee assessment would have no impact on our current operations; that was indeed the case, and remains so following today’s announcement.”

-with AAP