A Polish treasure-hunting duo is planning to put decades of hearsay to rest in the search for an underground train rumoured to be laden with Nazi gold - and has invited internet users to follow the action online.

History enthusiasts Piotr Koper and Andreas Richter said on Wednesday that the hunt in Walbrzych, western Poland, will be streamed in real time on the web.

"There will be a live stream," Christel Focken, a spokeswoman for the two men, told dpa, adding that information will also be posted on the project's website and Facebook page.

The dig begins on August 16 and the 35-strong team expects its first discovery within the first two days.

Last year, Richter and Koper claimed to have discovered an armoured German train in an underground tunnel between Wroclaw and Walbrzych using ground-penetrating radar.

Rumours have abounded in the region for decades that the Nazis had hidden gold and other treasures from advancing Soviet troops towards the end of World War II - but no stash has ever been found.

But the two men insist this is more than just a treasure hunt. The site may also have been used to hide the bodies of thousands of forced labourers, Focken said.

Not far from the suspected horde, the Nazi regime operated Projekt Riese, or "Project Giant," an ambitious tunnel construction project driven by slave labour which many workers did not survive.