Bidders on eBay are offering over €13,000 to get their hands on a wartime German encoding machine.

The portable Enigma encryption machine, made in 1941, is similar to ones whose messages were cracked by British code breakers at Bletchley Park in World War Two. It has a keyboard and a series of rotors designed to scramble messages.

The machine is believed to be the genuine article, but serial numbers which could prove its provenance have been removed.

"We've had it inspected by an expert who said that, due to its good condition, it looks very likely to have been in German state ownership at the time," said Alexander Urff of Sales Service, the Munich-based company selling the device.