VIENNA (Reuters) - Leopold Engleitner, the oldest known survivor of the Nazi concentration camps, has died at the age of 107, his biographer said.
Engleitner, a conscientious objector whose life was documented in the book and film "Unbroken Will", was imprisoned in the Buchenwald, Niederhagen and Ravensbrueck camps between 1939 and 1943.
He refused to renounce his Jehovah's Witness faith to win his freedom but was eventually released, weighing just 28 kilograms (62 pounds), on condition that he agree to spend the rest of his life working as a slave agricultural laborer.
He returned to work on a farm near his home town of Bad Ischl in Austria and was released from forced labor by U.S. troops in 1946 after a period in hiding in the mountains to escape a call-up to the German army.
Engleitner carried on his missionary work after the war while working jobs including a spell as a night watchman in a soap factory.
He became a public figure when Austrian author and film producer Bernhard Rammerstorfer published his biography and a documentary film about his life in 1999, which were translated into English in 2004.
He went on speaking tours in Europe and the United States and talked to students about his experiences through his last years, attending the U.S. premiere of a new Rammerstorfer documentary film about his life in November 2012.
"It's very hard for me to announce the painful news of the passing away of my best friend," Rammerstorfer wrote on his website.
The author said Engleitner had died peacefully in the company of Rammerstorfer's family on April 21.
Reporting by Georgina Prodhan; Editing by Angus MacSwan