Other movie roles were in ''Hotel Sahara'' (1951), in which Mr. Ustinov appeared as a beleaguered Arab hotelier; ''Beau Brummel'' (1954), with the actor as a pompous Prince of Wales; ''We're No Angels'' (1955), where he played a slick convict; ''Lola Montès'' (1955), as a ubiquitous circus master; ''The Sundowners'' (1960), playing an Australian loafer. Later roles included his portrayal of a Mexican general in ''Viva Max!'' (1969), a fraudulent doctor in ''The Treasure of Matecumbe'' (1976), a sadistic sergeant in ''The Last Remake of Beau Geste'' (1977) and Charlie Chan in ''Charlie Chan and the Curse of the Dragon Queen'' (1981).

In later years he also stylishly portrayed Hercule Poirot, Agatha Christie's eccentric Belgian detective, in the films ''Death on the Nile'' (1978) and ''Evil Under the Sun'' (1982) and in a series of television specials. Also on television, he narrated many fantasy, historical and science programs and supplied a multiplicity of voices on many of them.

Admirers praised his talent, stamina and discipline in channeling his efforts despite an appearance of flitting among many projects that some friends likened to disciplined chaos. He rated his satisfactions in this order: 1) writing novels, 2) writing short stories, 3) playwriting, 4) acting, 5) directing and 6) producing.

''Writing has always been my deepest love,'' he said in 1982. ''Acting is intrinsically easy. You're like a chameleon, adapting yourself to various circumstances and to what other people are writing. Writing is much more mysterious, and more personal.'' Among his novels were ''The Loser'' (1960) and ''Krumnagel'' (1971); his short stories included ''Add a Dash of Pity'' (1959) and ''The Frontiers of the Sea'' (1966). Other writings were ''My Russia'' (1983), ''Peter Ustinov in Russia'' (1988) and a 1977 memoir, ''Dear Me.''

He visited Russia often, before and after the breakup of the Soviet Union. In 1988 he flew to Leningrad, now St. Petersburg, for the opening of an art museum dedicated to his mother's family and housed in a building erected by one of his great-great-grandfathers. Also that year, he was host of a mini-series based on his book ''My Russia,'' describing the changes in Soviet society under Mikhail S. Gorbachev thus: ''It's been like an abscess bursting and health returning.''

Sir Peter's writing was usually praised for wit, literacy and insights, but the consensus was that his work, though clever and diverting, suggested more than it accomplished. Reviewers agreed that his early plays showed great promise, but over the years they increasingly criticized his writing as that of an undisciplined jack-of-all-trades who frittered away his talents and was at times self-indulgent and verbose. Still, the critic John Lahr hailed the spirited autobiography ''Dear Me'' as ''an unusually graceful memoir whose wit bears witness to Ustinov's generosity and seriousness.''

The entertainer maintained a frenetic professional pace for more than 50 years. Asked to explain his abhorrence of retirement, he replied, ''I've always considered life to be much more of a marathon than a sprint.''