Police used water cannon and made 70 arrests Saturday as they struggled to keep 700 neo-Nazis and even more leftists apart on the streets of Berlin, dpa reported.
The rightists had earlier announced a march through the capital's Lichtenberg district.
Mainly leftist opponents, determined not to let them pass, sat down on the road. Volleys of stones were thrown towards the neo- Nazis, who replied by hurling beer bottles in the other direction, witnesses said.
After warnings, the water cannon, mounted on riot-police trucks were used to drive the blockers off the roadway. Police said several demonstrators on both sides and one police officer were slightly hurt.
Police had deployed 1,600 officers in a bid to cordon the two crowds, and keep them to different routes and times, so that there would be no clashes, but mobile groups from the left managed to approach the neo-Nazis.
Both groups were exercising a constitutional right of freedom to demo nstrate. The neo-Nazis were demanding the right to set up a "nationalist" youth centre.
A police spokeswoman said the 70 arrested came from both sides of the conflict.