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PARIS — Seeking to disprove that it concealed works of art seized by the Nazi occupiers, France this week unveiled some 987 paintings, drawings and sculptures that have not been claimed by their owners or heirs since World War II.

But as five state-run museums, including the Louvre, Pompidou Centre and the Musée d'Orsay, opened exhibits of the works, a new controversy erupted.

The fray developed after the head of France's national museums said most of the works, including paintings by Renoir, Monet and Cezanne, were legally purchased during the war, and that few were looted from Jews.

"The documentation shows that the majority of these paintings were bought, clearly and publicly in the flourishing Paris art market," said Francoise Cachin, director of the national museum network, the Musées de France.

But the French section of the World Jewish Congress protested, accusing the museums of hiding the art for 50 years.

Serge Czajgenbaum, secretary general of the WJC's French section, said that the possessions of 66,000 Jewish families were looted by the Nazis. In July, 1940, the German ambassador to France, Otto Abetz, began inventorying Jewish artworks, he said.

"Within a few months, the embassy was the center of a huge art market," he added. "It was the fruits of massive pillaging of the Jews of France."

The Germans covered up their theft by selling works looted from Jews to collaborationist art dealers, who in turn sold them to buyers for German museums, he said.

"While admitting that a tiny portion of these artworks had been legally acquired, one cannot speak of a `flourishing art market' in Paris during the occupation, but rather of flourishing art trafficking, of theft, of plundering and selling stolen works," the WJC said.

Many said the French museum exhibits signalled the postwar generation's desire to shed light on France's wartime role.

But some said the government had to display the works after a damning report by France's state-spending watchdog, the Cour des Comptes, was leaked to the media in January.

That report accused France's state museums of making little or no effort to seek out the owners of some 2,000 artworks plundered during the war.

The government, which has formed a commission to investigate Jewish property looted by the Nazis, welcomed legitimate claims to the art. But the government apparently believes that few owners will surface.

"I want to show that the reality is more complex than the rumors which would lead us to believe that French museums have hidden away veritable masterpieces seized from Jewish families by the Nazis," Culture Minister Philippe Douste-Blazy said at a preview of the Musée d'Orsay exhibit, standing before a massive 1870 oil by Gustave Courbet, "The Cliffs of Etretat After a Storm."

The Musée d'Orsay exhibit also included several works by Monet, including his 1876 oil "Train in the Countryside" and "View of Argenteuil" from 1872; pastels by Degas; and a self-portrait by Cezanne.

Many of the works shown were accompanied by labels tracing their ownership to counter accusations that the art had belonged to Jews.

But several others — including Renoir's pastel "Head of a Young Girl," his oil "Meeting in a Garden" and Manet's watercolor "Turkeys and a Duck" bore the label, "Origin: Unknown."

Meanwhile, the French Foreign Ministry said it was returning three works, including the 1921 Picasso painting "Woman's Head," to the original owners' heirs.

Of 61,257 works that France recovered from Germany, 45,441 were returned to their rightful owners soon after the war.

The remaining 15,858 were displayed between 1950 and 1954 at the Chateau of Compiegne about 60 miles north of Paris. That exhibit drew about seven claims.