He died unexpectedly in Palm Springs, the Hamburg-based agency said in a statement on Thursday.
"His warmth of heart, his joie de vivre and his unwavering sense of justice will make him unforgettable," it added.
Born in Berlin, Kruger became one of the few German actors to succeed with an international career after the war. He made his breakthrough outside Germany in the British war film The One That Got Away.
He appeared alongside John Wayne in Hatari! and together with James Stewart and Peter Finch in The Flight of the Phoenix.
In 1963, the French drama Sundays and Cybèle, in which Kruger played a Vietnam war veteran who blames himself for the death of a Vietnamese child, won an Oscar.
The actor also received a number of awards in his native Germany.
Kruger also appeared on screen with Claudia Cardinale, Sean Connery, Yul Brynner, Charles Aznavour, Cathérine Deneuve and Orson Welles.
Kruger also launched his prolific career as an author in 1970 with his book Eine Farm in Afrika (A Farm in Africa). It told the story of the farm he bought at the foot of Mount Kilimanjaro, after falling in love with East Africa during the filming of Hatari!
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