BBC executives have launched a desperate search for an intimate diary written by the late Richard Burton that has gone missing after being lent to programme makers by the actor's widow.

The memoir, which contains frank and revealing insights into the thoughts and life of the late actor, has disappeared from the corporation's offices in White City, west London, where it was left in an unlocked cupboard in a production office.

The book, with several other personal items, was lent to the BBC for two weeks by Sally Burton, a former employee of the corporation, to contribute to a documentary screened last month on BBC2.

The items were returned to Mrs Burton's west London home in a taxi in March, in an unsealed box. She discovered the diary was missing three months later after returning from holiday. The memoir described the first year of his married life with Elizabeth Taylor in 1964. In the diaries he kept over the years, he gave honest accounts of how he was tormented by alcoholism and disliked the "luvviedom" that went with an acting career.

Scotland Yard detectives investigating the apparent theft have warned Mrs Burton, aged 53, that the memoir is unlikely to be recovered, although searches of internet sites are being conducted to see if it has been put up for sale.

A BBC spokeswoman said yesterday: "We are doing everything we can to try to locate it. We have to acknowledge that it is strongly possible it has been stolen ... but we haven't given up hope that it may be recovered.

"We have expressed our deep regret to Sally Burton for the loss of something which is obviously of great sentimental value to her, and historical value in itself.''

The Reputations documentary series, which drew on the books for a profile of Burton, revealed that he wrote: "I loathe loathe loathe acting. I loathe it, hate it, despise, despise – for Christ's sake – it."

Mrs Burton, an intensely private person, spoke for the first time on the Reputations programme of the grief she has suffered since her husband's death 17 years ago, and described the programme as "fantastic".

Flaws in his tempestuous relationship with Taylor were evident at the outset of their romance, the diary featured in Reputations revealed. She had been taken to hospital after what seemed to have been a suicide attempt when Burton tried to end the affair.

Despite his struggles, Burton was appreciated as one of the greatest actors of his generation. He died in 1984 at the age of 58.

He was most famous for his roles in Look Back in Anger, Who's Afraid of Virginia Woolf and Cleopatra.

He never, though, managed to fulfil his final goal. "I've played the lot: a homosexual, a sadistic gangster, kings, princes, a saint, the lot. All that's left is a Carry On film. My last ambition," he said.