An 89-year-old woman, who was sentenced to two years' imprisonment in Germany for incitement to hatred, was arrested on Monday after failing to show up for her prison sentence.

Ursula Haverbeck, dubbed "Nazi Grandma" by German media, is a notorious Holocaust denier who was found guilty of incitement in eight cases last year. She was expected to start her prison sentence in the town of Bielefeld last Wednesday, but she did not appear. Authorities issued an arrest warrant on Monday.

She was handed her most recent sentence for sending the mayor of Detmold, and the media, a letter in which she claimed Jews were never exterminated at Auschwitz.

In Germany, those who deny the Holocaust may be charged with incitement of hatred.

Haverbeck has been convicted of incitement several times before but had not served prison time. In 2015 she was on trial for saying the Holocaust was "the biggest and longest-lasting lie in history".

The Holocaust was the mass murder of six million Jews, who were killed by Nazis in the lead up to and during World War II.