Using a ground penetrating radar, 70-year-old Peter Lohr, says he discovered huge caverns in the ground under the Jonastal in Thuringia.
Furthermore, using a 3-D imaging technology he found five large metal objects in the cave, at least two of which he believes are atomic bombs.
The shape of the metal objects corresponds to the shape of a nuclear weapon, said Lohr, who is a trained mechanical engineer.
“The metal's been lying there for 71 years. At some point it will decay and then we will have a second Chernobyl on our hands” he warned tabloid Bild.
The authorities don't seem to be taking his concerns as seriously though.
“They just told me that I'm not allowed to continue my research anymore.”
This is of course not the first time that an a hobby researcher has made a fantastical claim about a hidden underground lair full of Nazi secrets.
Just last year, two amateur historians had international media on tenterhooks after claiming they had found a train in a hidden tunnel in Poland full of Nazi gold and other treasures.
After extensive searches of the site, qualified researchers said they could find no evidence the train existed.
Did Nazis develop a nuclear bomb?
That the Nazis did work on their own nuclear weapon is not just a theory believed by conspiratorial crackpots.
In July 2015 public broadcaster ZDF showed a documentary called “The search for Hitler's nuclear weapon”.
Among the evidence they cite is a Russian military report given to Stalin which claimed that the Germans had successfully developed a nuclear bomb.
Reputed historian Rainer Karlsch also published a book, "Hitler's Bomb", in 2005 which argued that the Nazis developed an atomic bomb.
Karlsch wrote that two tests on a small nuclear bomb had been carried out, one in October 1944, the next in March 1945.
The theory that the Nazis were in the process of developing a superbomb was first propagated by the leaders of the Third Reich themselves, who in the finals days and weeks of the war kept promising a “Wunderwaffe” (super weapon) which would turn back the tide of the Allied march.
But, according to Sven Felix Kellerhoff, an editor and historian at Die Welt, there is no evidence that his was anything more than propaganda.
None of the evidence presented by ZDF or Karlsch is credible, he wrote last year, arguing that reports gained by the Allies from informants do not change the fact that "at no point did the Nazis have the industrial capability to split plutonium or uranium in sufficient quantities to create a nuclear bomb."
He also noted that Nazi propaganda minister Joseph Goebbels did not once mention the construction of such a bomb in his diary.
“If neither Hitler's closest confidant nor the top level of the army knew anything about any such project, how likely is it really that it existed?", Kellerhoff concludes.