"At night the prisoners were held in a deep pit, previously used for the execution of Vilna's Jews, while during the day they worked to dig the mass graves, pile up the corpses on logs cut from the forest, cover them with fuel and incinerate them," the IAA said.
Bound in chains, the prisoners were fully aware that as they finished their horrendous task, they too would be murdered.
A secret group was then organized among them. For three months they dug a tunnel more than 100 feet in length, using only spoons and their bare hands. On the night of the April 15, 1944, the escape was made.
After cutting their leg shackles with a nail file, 40 prisoners crawled through the narrow passageway, only to be discovered and shot by the Nazi guards.
RELATED: Escape Tunnel' Found at Nazi Death Camp
Only 15 managed to get away into the forest, and of these 11 reached the Allied forces and survived the war.
A monument was erected after the war to the memory of the victims, but the exact location of the tunnel remained unknown until now.
"This discovery is a heartwarming witness to the victory of hope over desperation," IAA archaeologist Jon Seligman said.
"The exposure of the tunnel enables us to present, not only the horrors of the Holocaust, but also the yearning for life," he added.