Seurat sketch thought to be stolen by Nazis is seized from Paris art dealer

A long-lost sketch for one of the most famous French paintings of the late 19th century has been seized by police from an art dealer in Paris. The preliminary study by the pointillist artist Georges Seurat, painted on the lid of a cigar box, was assumed to have been stolen by the Nazis during the Second World War.

French investigators searching for looted Jewish-owned art want to know why the tiny painting, valued at €5m (£3.75m), has suddenly turned up in the hands of a French art dealer. The Etude de L'Ile de la Grande Jatte is one of more than 50 studies painted by Seurat between 1884 and 1886 for his celebrated painting of heavily clothed sunbathers on an island in the river Seine.

The completed canvas, Un Dimanche à la Grande Jatte, is 9ft by 6ft and owned by the Art Institute of Chicago. The study seized by French police shows almost the same scene but is painted on a cigar-box lid the size of a standard exercise book.

Like the finished canvas it uses the technique perfected by Seurat of painting not in brush strokes, but with thousands of tiny blobs, or points, of oil-paint. The study may well have been painted by Seurat on the island itself and taken to his studio as one of more than 50 preliminary sketches for the final canvas.

Its recovery coincides with an exhibition in Jerusalem this week of 53 paintings seized by the Nazis in France – including another Seurat – whose legitimate owners have not been traced. The exhibition, which moves to Paris in June, shows only a fraction of the 2,000 French-Jewish owned art works recovered from Germany after the war but still in the custody of the French state.

In the case of the Seurat study, the chain of ownership is reasonably well-established. It once belonged to the Jewish painter Paul Signac. In 1940, his widow Berthe Signac gave it to a French art dealer, André Metthey, for safe-keeping after Germany invaded France.

In 1945, when the Signac family tried to reclaim the painting, M. Metthey said it had been stolen by the Nazis. The work was added to the French list of "despoiled" art works. Two years ago, another French art dealer, Eric Turquin, asked the French Ministry of Culture for a certificate allowing him to sell the work abroad. He said the Seurat study had been brought to him by a client, Elias Chartouni.

Following a complaint by the heirs of the Signac family, an investigation was started by the French government agency which monitors trafficking in stolen art. The painting was seized in the past few days at M. Turquin's offices in Paris, police said yesterday.

A magistrate, Fabienne Pous, has been appointed to investigate "theft by persons unknown". She will try to trace the movements of the painting in the past 68 years and investigate claims and counter claims about its ownership.

In the 1880s, the Ile de la Grande Jatte was in open countryside and a favourite spot for strolling, bathing and boating. Now known as the Ile de la Jatte, it has been engulfed by the westward sprawl of Paris. The island has been almost entirely covered with up-market apartment blocks, in the shadow of the tower blocks of the business district of La Défense.