Cartier-Bresson was a master of candid photography
The widow of Henri Cartier-Bresson, who is credited with founding modern photo- journalism, says hundreds of his photos may still be on the black market.
The photos, which had been archived in France's National Centre for Contemporary Arts, suffered severe water damage from a leak in the 1990s.
Cartier-Bresson then agreed that the pictures should be destroyed. But some photos reappeared in 2001.
Martine Franck also accused the French state of negligence in the affair.
The French authorities have refused to comment on the affair.
Cartier-Bresson died in 2004 at the age of 95.
In the autumn of 1955, Cartier-Bresson held an acclaimed exhibition in the Louvre in Paris, displaying 426 photos dating from the 1930s through to post-war pictures taken in Russia, China, India and the United States.
The show toured eight different countries and in 1960 the photographer gave the collection to the French state, who archived it in the National Centre for Contemporary Arts.
But when the centre moved buildings 30 years later it was discovered that the pictures had been severely damaged.
Distraught, Cartier-Bresson agreed the photos should be destroyed. But somebody may have picked the images out of the bin.
Several pictures appeared at an art fair in Paris in 2001, while others turned up at auction and at restoration houses.
According to Martine Franck, who has spoken publicly about the episode for the first time this week, the black market sales upset Cartier-Bresson so much that he refused to leave any more of his works to the French state.
She said he believed it was incapable of looking after his photos properly.