Billionaire art dealer Guy Wildenstein, who is based in Paris and New York, has been formally accused of fraud after 30 valuable paintings and sculptures that had been missing for decades turned up in a police raid of his family's institute in Paris.

Mr Wildenstein claims the works found stored in a basement, including Edgar Degas drawings allegedly looted by the Nazis and a Berthe Morisot painting belonging to a client's heir, were "an oversight or error" made by his late father.

He has been placed under formal investigation by a French magistrate on a possible charge of "receiving fraudulently obtained goods," part of a tangled web of recent lawsuits and scandals involving the powerful art-dealing family.