Tolstoy fights to protect secret world of Patrick O'Brian

Relatives of the dead writer Patrick O'Brian are planning a legal battle to prevent his diaries - which they fear contain embarrassing details of his colourful private life - ever being published.

O'Brian, whose meticulously researched seafaring novels have sold 6 million copies worldwide, kept a faithful diary for 27 years but its contents are strictly guarded.

His immediate family, including his stepson, the historian Count Nikolai Tolstoy, are fearful the journals of the writer, whose books were made into the blockbuster movie Master and Commander: The Far Side of the World, could now be sold by trustees against their wishes. The family claims O'Brian expressly asked for the diaries and his other correspondence to be destroyed when he died.

O'Brian created a life for himself that was as fictional as his naval tales, claiming to be Irish while actually of Anglo-German stock, and glossing over a past in which he had abandoned his first wife and children. Even his surname was an invention - his birthname was Russ. He counted Picasso among his friends and his fans included Charlton Heston and Iris Murdoch.

The latest row has been sparked by the publication next week of an incomplete novel - only three chapters long - on which O'Brian was working at the time of his death four years ago.

The sole beneficiaries of the estate - Mr Tolstoy's four children and two children of his sister Natasha - believe they should have been consulted about the plan to sell the manuscript to a publisher. Mr Tolstoy said his stepfather was fiercely private and would have been "mortified" that an unpolished work was being made available.

Mr Tolstoy's son Dmitri said that O'Brian would have been angered by the prospect of his diaries being published. "My stepgrandfather would be furious - it goes directly against his wishes," he said.

The family is now preparing for a legal battle to have the trustees of the estate removed and to prevent the diaries from being made public.

O'Brian won fans for the historical detail and carefully constructed stories which formed the 20-volume series of adventure on the high seas. The writer was working on his 21st book when he died. Just 65 handwritten pages were left and these will be published by HarperCollins on 4 October as The Final Unfinished Voyage of Jack Aubrey.

But Mr Tolstoy said publication has been arranged without the agreement of the estate's six beneficiaries. "He felt strongly that you don't pry behind a writer's work," he said.

HarperCollins said the publication was justified. A spokeswoman said: "It serves as a rare insight into the mind of a master at work and we think it will be of huge interest to fans of Patrick O'Brian."