In late 2014 Austrian filmmaker Andreas Sulzer carried out excavations at St. Georgen an der Gusen near the northern city of Linz and found steps leading down to what he believed was an entrance to the underground site.
He believed it was connected to the vast "Bergkristall" subterranean complex where thousands of slave workers are known to have died making Messerschmitt aircraft parts at the end of World War II.
Following Sulzer's claims, engineers drilled down 122 metres (400 feet) but found no underground cavities or any nuclear materials, the panel of archaeologists, historians and other experts said.
Asked at a news conference in Perg near St. Georgen whether he could rule out there being an undiscovered network of tunnels, professor Bertrand Pelz from Vienna University said: "All our evidence suggests: yes".
The steps found by Sulzer meanwhile did date back to the Nazi era but were part of an SS shooting range, the panel said.