The search for a lost Nazi gold train is back on.

Last August, two amateur treasure hunters said they had "irrefutable proof" of the existence of a World War II-era Nazi train, rumored to be filled with stolen gold.

Piotr Koper and Andreas Richter. Screen grab/TVP Andreas Richter and Piotr Koper claimed they used ground-penetrating radar to locate the train, which is somewhere alongside a railway between the towns of Wroclaw and Walbrzych in southwestern Poland.

"The train isn't a needle in a haystack," Andrzej Gaik, a retired teacher and spokesman for the renewed effort to search for the train, told Agence France-Presse.

"If it's there, we'll find it," Gaik said.

'There may be a tunnel. There is no train.'

Journalists visit the underground tunnels. Reuters In December, after analyzing mining data, Polish experts said there was no evidence of the buried train.

Janusz Madej, from Krakow's Academy of Mining, said the geological survey of the site showed that there was no evidence of a train after using magnetic and gravitation methods.

"There may be a tunnel. There is no train," Madej said at a news conference in Walbrzych, according to the BBC.

Koper insists that "there is a tunnel and there is a train," and that the results are skewed because of different technology used, The Telegraph reports.

Local folklore

According to a local myth, the train is believed to have vanished in 1945 with stolen gold, gems, and weapons when the Nazis retreated from the Russia.

Tadeusz Slowikowski. Reuters

During the war, the Germans were building headquarters for Nazi leader Adolf Hitler in Walbrzych's medieval Ksiaz Castle, then called the Furstenstein Castle.

Below the castle, the Germans built a system of secret tunnels and bunkers, called "Project Riese."

The train is in one of these hidden passages, says Tadeusz Slowikowski, the main living source of the train legend. Slowikowski, a retired miner who searched for the train in 2001, believes the Nazis blew up the entrance to the train's tunnel.

"I have lived with this mystery for 40 years, but each time I went to the authorities they always silenced it," Slowikowski told The Associated Press. "For so many years. Unbelievable!"

Slowikowski believes it is near the 65th kilometer of railway tracks from Wroclaw to Walbrzych.