An Austrian organization that tracks the fate of Nazi concentration camp inmates says one of the oldest known survivors has died at the age of 107.

The Mauthausen Committee said Thursday that Leopold Engleitner died April 21.

After refusing to renounce his faith as a Jehovah's Witness, he survived three concentration camps and forced labour between 1939 and 1945.

He weighed just 28 kilograms — about 60 pounds — on release from the Ravensbrueck camp in 1943 after he agreed to work as farm slave labourer. Later ordered to report to Hitler's army, Engleitner hid in the Tyrolean countryside until after the war ended.

Engleitner's life was documented in the book and film Unbroken Will, by Austrian filmmaker and author Bernhard Rammerstorfer, and he toured Europe and America to share his experiences.

The oldest known survivor of the camps is Alice Herz-Sommer, 109, who lives in London. She was confined in the camp in Terezin, or Theresienstadt, in Germany.