In an official ceremony, Culture Minister Aurelie Filippetti returned the works to the grandchildren and great-grandchildren of the original owners who are now dead — calling it a "gesture toward justice."
They include "Madonna and Child," by 14th century master Lippo Memmi and "Portrait of a Woman," an 18th century canvas by an unknown artist.
The Memmi masterpiece, painted on wood, was looted in 1944 from a Jewish Romanian banker, Richard Soepkez, who lived in the French Riviera city of Cannes.
It was returned to his grandson Nicholas Florescu, who travelled to France for the ceremony from his hometown of Houston.
"It's unbelievable what's happened," said 62-year-old Florescu, visibly moved.
"I mean think about all these years. It was not even in the cards but the French government was very helpful in finding this and we owe a great gratitude to them," he added, saying he will now travel to Antibes where his gravely ill 89-year-old father, Soepkez's son, still resides to tell him the news.
The third painting, "Mountain Landscape" by Flemish artist Joos de Momper (1564-1635), was destined for display in the art gallery Adolf Hitler wanted to build in his hometown of Linz, Austria.
This restitution now brings the number of looted paintings returned by France to their rightful owners to 10 in less than a year — part of an ongoing effort to return hundreds of looted artworks Jewish owners lost during the war.
At the end of the war, with Hitler dead and European cities rebuilding, artworks were left "unclaimed" and many thousands that were thought to have been French-owned ended up in the country's top museums, including the Louvre.
Many of the 100,000 possessions looted, stolen or appropriated between 1940 and 1944 in France have been returned to Jewish families, but France says some 2,000 artworks still lie in state institutions.
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