Clashes between neo-Nazi demonstrators and far-left counter-protesters overnight in the northern German port city of Hamburg left 38 police officers injured, police said Sunday.
Security forces were pelted with rocks, bottles and fireworks and responded by turning water canon and pepper spray on the rioting groups who turned out at a march by the far right.
At least two parked cars and a police cruiser were set ablaze.
Police, who deployed 4,400 officers to keep the peace between the two sides, took 63 demonstrators into custody and formally arrested another 17.
Around 3,500 people, mainly from the hard left, turned out to block a procession of about 700 right-wing skinheads, while more than 10,000 people attended a separate, peaceful rally against neo-Nazis in front of city hall.
Police chief Wolfgang Kopitzsch said he was pleased "that so many people demonstrated peacefully for an open and tolerant Hamburg" but said "nothing could justify" the clashes.
Organised marches by neo-Nazis in Germany generally meet with much larger counter-protests but are often accompanied by violence between the far left and far right.