French police have thwarted an alleged plot to raid Fontainebleau palace near Paris.
Five Spaniards and a man thought to be Chinese are in custody. They deny any involvement in the post-Christmas raid.
Police believe the six were targeting Napoleon III’s treasures from Empress Eugenie’s Chinese Museum and are probing possible Chinese mafia links.
Fontainebleau was targeted only four years ago. Some 20 priceless artefacts were taken and never recovered.
Spanish police were first alerted to a potential plot to target a French national museum specialising in Asian art.
They passed information to Europol, along with names and photos of some of the suspects.