Over 100 Islamists were detained in Bonn on Saturday night after they attacked a far-right rally and injured 29 police officers.
Trouble kicked off when about 30 members of the Islamophobic Citizens Movement For North Rhine-Westphalia, which has angered Muslims by showing cartoons depicting the Prophet Mohammed, paraded through a part of town with a large population of Middle Eastern and Asian migrants.
When Islamist counter-protesters started attacking security forces surrounding the march, police detained 110 of them.
Most of them had been released by Sunday but prosecutors opened criminal investigations against them on suspicion of breach of the peace.
Another counter-protester who is suspected of stabbing two police officers remains in custody.