Rupert Murdoch's top newspaper lieutenant in Britain is to leave his post at the end of the year, it was announced Sunday, heralding the start of a major shake-up at parent company News Corporation.

The sudden departure of Tom Mockridge, chief executive since July 2011 of News International, which encompasses The Sun, The Times, and The Sunday Times in London, was made public by Murdoch himself.

It sets the stage for a restructuring of News Corporation into two separate divisions with a publishing arm controlling newspapers and an entertainment business controlling the company's television and film interests.

That recently announced move came in the wake of heavy criticism, including from shareholders, about the company's handling of a phone hacking scandal that erupted in Murdoch's media empire in Britain.

In the wake of the illegality, the News of the World newspaper was closed and a major police investigation is ongoing with court cases against two former Murdoch editors scheduled to take place next year.

Mockridge's decision to leave also comes amid much speculation that he was to miss out on the top job at News Corp's new publishing division.

The favorite for that post is reportedly Robert Thomson, the top executive at the Murdoch-owned Wall Street Journal and Dow Jones Newswires, and a former editor of The Times in London.

Murdoch, chairman and chief executive of News Corp, said in a statement that it had been his pleasure to have Mockridge as a colleague for 22 years.

"Tom has always been a skilled executive and a trusted friend. His decision to step down is absolutely and entirely his own," the magnate said.

"I am sorry to see him leave us but I know he will be a great success wherever he goes."

Murdoch, 81, added that Mockridge's long tenure encompassed "his early days with our newspaper group in Australia, his incredible work building SKY Italia," as well as "his steadfast leadership of News International."

News Corp, one of the world's biggest media-entertainment conglomerates, owns the 20th Century Fox film studios and Fox broadcasting operations, along with cable television assets, newspapers in the US, Britain and Australia.

It also owns the HarperCollins publishing house.

A company statement said Mockridge joined News Ltd in Australia in 1991, was CEO of Foxtel from 1997 to 2000, and spent a year with Murdoch's son James at Star TV.

He then transferred to New Zealand as CEO of what was then the company's newspaper operations and Chair of SkyNZ, before moving to Italy in 2002 to create Sky Italia.

Mockridge then took the role of CEO European Television, and serves on the boards of BSkyB and Sky Deutschland and is Chair of Fox Turkey.