Weissenberg suffered from Parkinson's disease. He died Sunday in Lugano, Switzerland where his family had settled.
An only child, Weissenberg recalled sharing "musical joys" learning piano and listening to recordings and concerts with his mother, before studying piano with a famous Bulgarian composer, Pancho Vladigerov.
Weissenberg recalled in an essay on his website that when he and his mother tried to flee German-occupied Bulgaria for Turkey in 1941 with faked ID and visa papers, they landed in "an improvised concentration camp" in Bulgaria for people crossing the border illegally. He said the German-guarded camp was probably intended to send people to Poland - and extermination.
They arrived with few belongings other than a small bag, a large cardboard box, a few sandwiches and an old accordion given him as a birthday gift by a wealthy aunt.
And they were lucky: After three months in the unspecified camp, a German guard who enjoyed listening to him play Schubert on the accordion helped them escape by train.
"It was the same officer who decided one chaotic day to come and fetch us hurriedly, bring us to the station, push our belongings (still the cardboard box) through the door, literally throw the accordion through the window of the compartment," he recalled.
The guard told his mother, "Good luck" in German, then vanished. A half-hour later, they were over the border, and no one asked for passports. The next day they arrived in Istanbul.
They wound up in Israel, where he performed Beethoven with the Israel Philharmonic led by Leonard Bernstein. After the war, he moved to New York to study at the Juilliard School of Music. Then, in the 1950s, he moved to Paris and became a French citizen.
In 1966, he played Tchaikovsky with the Berlin Philharmonic led by von Karajan. In later decades, he gave numerous master piano classes, and his recordings of classics by composers such as Liszt, Schumann, Stravinsky, Rachmaninoff, Chopin and Brahms became well-known.