PARIS — A Paris court convicted two auctioneers and 33 other people working for France’s biggest auction house Tuesday in a vast, long-running scam to steal thousands of valuable items worth millions of euros.

The works included a Courbet painting, Chagall and Matisse lithographs, stage costumes of famous French mime artist Marcel Marceau, a Ming-period Chinese tray and a 2.08-carat diamond.

The case involved about 50 people who worked at Hotel Drouot, the biggest, oldest and most famous French auction house. They were charged with gang-related theft, conspiracy to commit a crime or handling of stolen goods.

One auctioneer was handed a 12-month suspended prison term and a 30,000-euro ($33,500) fine, and the other an 18-month suspended prison term and a 25,000-euro fine. Two auctioneers were acquitted.

Of the 33 auction workers convicted, 19 were sentenced to prison terms from six months to 18 months, and the other 14 were given suspended sentences. Twenty-seven were sentenced to fines from 5,000 to 60,000 euros. Eight auction workers were acquitted.

The court ordered the dissolution of the company that employed the auction workers and worked with Drouot. The company, known under its acronym UCHV, is also ordered to pay a 220,000 euro fine.

The workers, nicknamed the “red collars” after their uniforms, were in charge of transporting the objects going on auction. Some of the workers were found guilty of stealing valuable items during estate inventories and later sold some of them with the active or passive complicity of auctioneers.

The stolen items were first stored in more than 100 containers in a warehouse outside Paris in order not to arouse suspicions of heirs. Then, after a period of several weeks or months, some of the objects were sold at Drouot auctions with the help of some unscrupulous auctioneers.

The number of stolen pieces discovered in the containers was so huge that investigators couldn’t give a precise count but said the total loot weighed at least 250 metric tons.