French cultural officials said 15 pieces of "priceless" art have been stolen from a Chinese museum south of Paris, including a replica crown of the King of Siam given to France's emperor in the mid-19th century.
The Culture Ministry said the break-in before dawn on Sunday at the Chinese Museum at Fontainebleau Castle was over in less than seven minutes.
Other items stolen were a Tibetan mandala and a Chinese chimera in cloisonné enamel from the reign of the emperor Qianlong (1736-1795).
Jean-Francois Hebert, who runs the Fontainebleau castle, said it was a "very big shock and trauma."
"We think they were very determined, knew exactly what they were looking for and worked in a very professional manner," Hebert said.
"They were among the most beautiful pieces in the museum," he said, adding that the Chinese museum was one of the most secure places in the castle.