Historic jewellery stolen in a spectacular robbery at a Dresden museum last year has been reportedly offered for sale on the dark web.

Irreplaceable antique jewellery estimated to be worth as much as €1bn (£850m) was feared lost after it was stolen from the city’s Green Vault museum in November in what is believed to be the biggest jewel heist since the Second World War.

But an Israeli security company claims two of the missing items have now been offered to its investigators for €9 (£7.6m).

They include the famous “Dresden White”, a 49-carat diamond of exceptional purity that is the most valuable missing item.

The CGI Group said its investigators were offered two of the missing items in an online chat.

"All information was given to the Dresden public prosecutor's office in real time," Zvika Nave, the company's CEO said.

The German authorities have not commented on the claim, and it is not clear how seriously the alleged offer is being taken.

“At the moment we cannot report anything new in the investigation,” said a spokesman for German prosecutors.

It was feared the baroque jewellery was too famous to sell intact and that the robbers would break it up so diamonds and other precious stones could be sold individually.