Oscar-winning British actor and playwright Peter Ustinov, one of the world's best loved raconteurs and mimics, has died at the age of 82.

Author of more than a dozen books and even more theatrical works in a career spanning more than 60 years, Ustinov died of heart failure in a clinic near his home on the shores of Lake Geneva on Sunday night, his family said.

The actor and humorist, who was also well known for charity work, had been in hospital since shortly after Christmas when he was taken ill on his return from a holiday in Thailand.

The United Nations' Children's Fund (UNICEF), with whom Ustinov had a long association, called him one of its "most effective and beloved" partners. "The children of the world have lost a true friend," said UNICEF chief Carol Bellamy.

Ustinov, who spoke more than half a dozen languages, won Oscars for his roles in the films "Spartacus" and "Topkapi."

The multi-talented entertainer, who was knighted by Britain's Queen Elizabeth but did not like to be known as "Sir Peter," finished his last film as an actor, about the life of 16th century Reformation leader Martin Luther, late last year.

Although confined to a wheelchair by diabetes and a weak heart, he continued to appear in public until his final illness, delighting television audiences across Europe with his witty stories and raising money for charities, particularly UNICEF for which he was an ambassador.

RICHLY VARIED LIFE

He led a richly varied life as playwright, novelist, film director, academic and as an active campaigner against war.

He was Chancellor of the University of Durham and shortly before his death, the University of Vienna inaugurated the Ustinov Institute, dedicated to studying prejudice and its impact on people, politics and conflict resolution.

"This was something that inspired him a lot. He wanted his ideas for the future to become a reality," Igor said.

Raised in Britain of Russian parentage, Ustinov was a London revue star as a teenager and wrote his first play at 19. He made his first feature film at 25.

He starred in, produced and directed his own plays, including Romanoff and Juliet, in London, New York, Berlin, Paris and Rome. He wrote novels to fill in time while hanging around on Hollywood film sets.

Among his best-known film roles was that of Hercule Poirot in screen versions of the stories of British mystery writer Agatha Christie's most famous detective. He directed seven feature films, among them the much-applauded Billy Budd in 1962, staged opera and was a noted photographer.

"He was one of the funniest men I have ever met," said Ustinov's biographer John Miller. "He had enough careers for about six other men. He was phenomenally busy."

Ustinov was the first to admit that laughter had been a life-long drug, confessing: "I was irrevocably betrothed to laughter, the sound of which has always seemed to me to be the most civilized music in the world."

He was once asked what would be his ideal epitaph.

With a familiar twinkle in his eye, he swiftly decided on the perfect inscription for his tombstone: "Keep off the grass."