The arrested person is accused of belonging to a group of left-wing extremists who are "suspected of being part of a criminal organization" and who have carried out attacks that "have led to serious bodily harm" and material destruction. He is also suspected of document forgery.
The attacks took place in 2019 and 2020, as well as at a neo-Nazi international gathering in Budapest in May 2023.
Four people in the group were sentenced to prison last year for attacking neo-Nazis.
Germany's Ministry of the Interior welcomed the arrest, and Interior Minister Nancy Faeser (Social Democratic SPD) said in a statement that "left-wing extremist groups pose a serious threat".
The leader of the group, named with only their first name and the initial of their last name according to German practice, was sentenced last year to more than five years in prison for attacking neo-Nazis.
"Opposing right-wing extremists is respectable", but attacking them with physical violence is still "a serious criminal act", said Judge Hans Schlüter-Staats when the verdict was announced.
