Two police officers suffered serious head injuries as they escorted a politician through a throng of activists protesting against a congress held by the far-right Alternative for Germany in the western city of Essen.
Unknown assailants kicked the officers in the head after forcing them to the ground, a police statement said. They were taken to hospital. Seven other officers suffered less serious injuries. The assailants were able to escape into the crowd.
Activists and police clashed throughout the day.
Interior Minister Nancy Faeser condemned the attacks. "We need strong democratic forces and peaceful protest against right-wing extremism and racism. Violence cannot be justified," she posted on X.
She expressed her thanks and respect to the police and wished the injured officers a speedy recovery.