Actor Roger Moore, who won international fame playing British secret agent James Bond, has died of cancer at aged 89, his family said.

His 12 years as Bond, the British agent with a voracious appetite for danger and sex, made Moore a millionaire and a heart-throb the world over.

"It is with a heavy heart that we must announce our loving father, Sir Roger Moore, has passed away today in Switzerland after a short but brave battle with cancer," his three children announced Tuesday in a statement on the actor's official Twitter account.

The son of a London policeman, Moore once said the upper-crust image he portrayed both on and off the screen was a carefully nurtured cover for his shyness and timidity. He also said he was terrified of playing the sex scenes which were a key part of the Bond movies.

"I couldn't walk into a restaurant on my own for 20 or 30 years ...," he once said, saying that all changed when he found fame in the role. "(But) that's not really me. Timid me would rather stay home and have a sandwich."

In reality, he was terrified by the stunts he had to perform as James Bond, and would steel himself before facing the cameras in the sex scenes with a mixture of valium and beer.

Moore's big breakthrough as an actor came in 1962, when he won the part of The Saint in a popular television series of the same name. In this role, he honed his image of the urbane Englishman with a stream of damsels to rescue from distress.

In 1973 came the coveted part of James Bond, who held cinemagoers across the world in thrall.

Moore, who replaced Sean Connery as 007 and was the third actor to take on the role, starred in seven Bond movies including Live and Let Die, The Spy who Loved Me and Octopussy.

He moved to the United States to become a tax exile.

"I don't see why a chap shouldn't do what he likes and live where he wants on his money, and the British government, which allows talent to go abroad because of taxation, has only itself to blame," he said in 1989.

After handing over the role to Timothy Dalton, Moore went into semi-retirement, living a millionaire's life and travelling between his homes in Los Angeles, Switzerland and France.

In 1991, he became an ambassador for the United Nations Children's Fund UNICEF, a role he retained until his death.

"With the passing of Sir Roger Moore, the world has lost one of its great champions for children - and the entire UNICEF family has lost a great friend," the agency's executive director Anthony Lake said in a statement.

Moore is survived by his fourth wife, Scandinavian socialite Kristina "Kiki" Tholstrup, whom he married in 2002, and by his three children from an earlier marriage, Deborah, Geoffrey and Christian.