Officers from the Railway Security Guards walk on tracks in an area where a Nazi train is believed to be at, in Walbrzych, southwestern Poland, on Monday.

AFP/Warsaw

A regional governor in Poland voiced serious doubts on Monday about the alleged discovery of a Nazi gold train, days after a deputy culture minister said he was "more than 99% sure" one had been found.

"There is no more proof for this alleged discovery than for other claims made over the years," Tomasz Smolarz, governor of the southwestern region of Lower Silesia, told reporters.

Two anonymous fortune hunters claim they have pinpointed the Nazi-era loot.

"It's impossible to claim that such a find actually exists at the location indicated based on the documents that have been submitted," Smolarz said, adding that he had set up a special unit including historians and geologists to scrutinise the alleged discovery.

He also said police and other security services are blocking off the presumed location of the train along a stretch of active railway tracks in a bid to prevent accidents amid an unprecedented influx of treasure hunters.

Global media have for days been abuzz with talk of trains full of jewels and gold stolen by the Nazis after the two men - a German and a Pole - claimed to have found an armoured train car buried near the city of Walbrzych.

Radar image

On Friday, Polish Deputy Culture Minister Piotr Zuchowski said he had seen a convincing ground-penetrating radar image of the alleged Nazi train.

"I'm more than 99% sure such a train exists, but the nature of its contents is unverifiable at the moment," Zuchowski told reporters, adding that he could make out platforms and cannons on the photo.

"The fact that this train is armoured suggests there could be valuable objects inside" including artworks, archival documents or treasures, Zuchowski added.

Smolarz said on Monday he had not seen any such image.

The World Jewish Congress has asked that any valuables found that once belonging to victims of the Holocaust should be returned to their owners or heirs.

Zuchowski said someone who had been involved in hiding the train, which is over 100 metres in length, had disclosed its location before dying.

Rumours of two special Nazi trains that disappeared in the spring of 1945, towards the end of World War II, have been circulating for years, capturing the imagination of countless treasure-hunters.

The lore is fuelled by a massive network of secret underground tunnels near Walbrzych - including around the massive Ksiaz Castle - that Nazi Germany built and where legend has it the Third Reich stashed valuables.