Two men claim to have discovered an armoured train car full of Nazi treasure but will keep its location secret until Polish authorities guarantee them a 10% cut.

Two residents of the town of Walbrzych in Lower Silesia told authorities of the discovery in a note in which they also outlined their offer, reported Polish news site Town authorities would not comment on the letter. Under Polish law, finders can keep up to 10% of the value of treasure.

Historians told local media that as the Red Army closed in on the city of Wroclaw, the Nazis loaded gold on to a train, which was sent in the direction of the Owl Mountains on the Polish/Czech border, where Walbrzych lies.

During the Second World War, the Nazis constructed a vast underground complex called Riese, or Giant, in the mountains. Some speculated the tunnels were intended as a residence for Adolf Hitler but experts argue they were intended to house armament factories as allied bombing of Germany intensified.