Horst Mahler, 81, a co-founder of the 1970s far-left Red Army Faction terror group who later swung violently far-right, was detained in the city of Sopron in Hungary near the Austrian border, police reported.
The arrest comes soon after Mahler said he was seeking political asylum in Hungary, according to the Mitteldeutsche Zeitung.
Mahler, 81, wrote in a post published online that he had requested asylum from Hungarian Prime Minister Viktor Orbán due to “political persecution”.
He further explained that the “persecution” had been prompted by the publication of his written work entitled “The End of Wanderings - Thoughts on Gilad Atzmon and the Jewish people”. The work refers to British-Israeli jazz saxophonist Gilad Atzmon, who has been accused of anti-Semitism and Holocaust denial.
Mahler was one of the original members of the Red Army Faction - also known as the Baader-Meinhof Group - which engaged in bombings, assassinations, kidnappings, bank robberies, and shoot-outs for three decades.
He later made a dramatic swing to the far-right, joining Germany's most radical extreme-right party, the NPD, between 2000 and 2003 before quitting because he found it "outdated".
Mahler received two concurrent prison terms of five and six years in 2009 for disputing that Nazis had systematically slaughtered six million European Jews during the Second World War. Denying the Holocaust is a crime in Germany.
He was temporarily released in 2015 because of ill health and was due to continue serving his prison sentence in the eastern city of Brandenburg on April 19th but failed to show up, according to German newspaper Taz.
Mahler has called the Holocaust "the biggest lie in history", praised the September 11th 2001 attacks on the United States, and given a Hitler salute to a Jewish journalist in an interview.