German left-wing activists have clogged the streets of Berlin in an effort to stop a planned far right parade from going ahead.
Earlier, a small group of Neo-Nazis gathered in the east of the city despite anger in Germany at plans to allow such groups to demonstrate.
After overnight clashes between police and protesters in Hamburg some 7000 officers were in the capital to try and keep order.
In spite of that, trouble broke out when hundreds of left-wingers gathered to block the planned route of the right-wing march.
Dozens sat on the ground, and at least one arrest was made as police removed them by force.
Demonstrations traditionally take place on May Day in Berlin, often leading to violence.
Last May, the capital saw some of its worst riots in in more than 4 years.