FBI investigating missing ancient treasures from British Museum

Mr Birbiglia, who worked for an antiquities gallery at the time, said he was “completely shocked” when the FBI contacted him. He said he probably bought the gems in order to sell them on, adding “I can’t even remember any of it”.

Mr Birbiglia told the special agent he could not remember anything about the gems. He asked the FBI for more information, such as pictures, so that he could try to identify where they may have ended up.

Neither the FBI agent, the museum or British police followed up with him – said Mr Birbiglia – so the two gems have not yet been tracked down by the authorities.

“The whole thing just seemed like they [the FBI] were blowing it off,” he said. “He [the agent] didn’t try very hard.”

The BBC understands the FBI has also assisted with the investigation of 268 items in the Washington DC area that were sold by the same seller.

A source close to the buyer told the BBC he bought items from sultan1966 over eBay – subsequently dealing directly with the same seller by email – and that he paid up to £7,000 for the items. According to the source, the seller used the name of “Paul Higgins” during the transactions.

The BBC believes gems have now been handed over to the British Museum, where work to prove ownership is ongoing.

But the US is not the only place where items sold by the seller may have ended up.

Danish antiquities dealer Dr Ittai Gradel, who first alerted the museum to thefts, has tracked down artefacts that were sold to buyers in several cities – including Hamburg, Cologne, Paris and Hong Kong.

Some of the gems which he bought himself in good faith, and then sold on to another private collector, ended up on display in the Deutsches Edelsteinmuseum in Idar-Oberstein, Germany. They were on loan to the museum for an exhibition.

One gem is thought to be a rare, 2nd Century head of the Greek hero Hercules made from obsidian, a type of volcanic glass.

Estimated to be worth thousands of pounds, the gem was one of the prize exhibits and appeared as a full-page photograph at the beginning of the exhibition’s catalogue.