News Corp chief Rupert Murdoch has filed to divorce his third wife, Wendi Deng, after their marriage became "irretrievably broken," his spokesman said.

Murdoch's Chinese-born wife gained notoriety in 2011 when she leapt to defend her husband from a pie-wielding protester. The divorce comes as News Corp is being split into independent publishing and entertainment firms.

"I can confirm for the record that Rupert filed in New York State Supreme Court this morning for divorce," his spokesman Steven Rubenstein told AFP.

Deng, 44, is 38 years younger than Murdoch, who is Australian-born but now a US citizen and is 82 years old.

They were married in 1999 aboard a private yacht that Murdoch had reportedly bought for his retirement, and they have two daughters, Grace and Chloe.

The news comes two days after News Corp shareholders approved a plan to split the Murdoch-led conglomerate into two independent firms.

One company will focus on news and publishing and retain the News Corp name. The other will concentrate on television and film and will be called 21st Century Fox.

Murdoch will remain in charge of both firms after the split, as chairman and chief executive of 21st Century Fox, and executive chairman of the new News Corporation.

Deng holds no formal role in the company but had been a longtime presence at her husband's side.

She met Murdoch while working at his Star Television company in Hong Kong, where former colleagues have described her as an expert networker with big ambitions.

Born in the eastern Chinese city of Xuzhou in 1968 -- at the height of the Cultural Revolution -- she left China at 19 to study in the United States. She graduated from the Yale School of Management in 1996.

Murdoch has spent a lifetime building his News Corp empire from a single Australian newspaper he inherited.

He moved to London where his purchase of the weekly News of the World in 1969 gave him a high-profile foothold in the British market. He went on to buy The Sun, a daily which he turned into a popular and big-selling tabloid.

The success of his London-based newspapers helped finance his 1981 purchase of The Times and Sunday Times, both prestigious broadsheets, in an acquisition that met with intense opposition from parts of Britain's establishment.

He relocated to the United States where more bold acquisitions followed and where he became a naturalized US citizen in 1985.

The conglomerate made a string of high-profile acquisitions, including the Fox broadcast and Hollywood studios, and the Wall Street Journal.

His youngest son James, 40, is believed to be the heir apparent to the media-entertainment empire.

James oversaw the closure of the the 168-year-old News of The World tabloid, which folded on July 9 after the revelation the tabloid hacked into the phones of murdered teenager Milly Dowler and the families of dead soldiers.

James was named News Corp's deputy chief operating officer in March 2011 and serves as chief executive of the news and entertainment giant's international operations.

In 1998, Murdoch and his second wife, Anna, separated after 32 years of marriage. She then filed for divorce in California courts.

The three Murdoch children from his second marriage -- Elizabeth, Lachlan and James -- have worked for the family empire or served on the board of directors.

Murdoch previously was married to Patricia Booker, an Australian flight attendant, with whom he had one daughter.