Media mogul Rupert Murdoch's decision to file for divorce was a bolt from the blue, not just for outsiders, but also for his wife, Ms Wendi Deng, the Daily Mail reported, quoting her friends.

The 82-year-old was seen to be keeping to his normal schedule up till last Tuesday, when he cancelled an appearance at a Los Angeles gala.

Last Thursday, Mr Murdoch filed for divorce in a New York State Supreme Court. The filing said that the "relationship between husband and wife has broken down irretrievably".

By most accounts, the couple had grown apart and spent long stretches away from each other. But people close to the Murdochs did not expect the mogul to divorce his 44-year-old wife.

A close acquaintance, real-estate billionaire Donald Trump, said he was stunned by the filing.

"I had no idea anything was wrong," Mr Trump told the Mail.

"I am friends with both Rupert and Wendi. They are great people. It always seemed a great marriage. I am sad for both of them."

Another friend, who did not want to be named, said: "She was totally blindsided by this. She said she had no idea it was coming...she never thought Rupert would want to go public and admit the marriage was a big mistake."

The Mail also reported that Mr Murdoch had told his son, Lachlan, that he had made a mistake in marrying Ms Deng.

In 1999, Mr Murdoch married Ms Deng in front of 82 guests on board his 47m yacht, the Morning Glory, shortly after ending his second marriage to his wife of more than three decades, Ms Anna Maria Torv.

Mr Murdoch had three children with Ms Torv: Lachlan, James and Elisabeth.

He divorced his first wife, Ms Patricia Booker, in 1967.

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