White and black youths clashed overnight Sunday on the outskirts of the German capital Berlin, leaving four injured, police said.
Police added that they suspected the whites may have been racist as two of the four arrested were neo-Nazis and one of the injured was an Ethiopian.
Witnesses said racist epithets were heard when the fight began, according to the German news agency DPA.
Black groups around the capital had complained that neo-Nazis had in effect turned some housing estates and small towns into "no-go areas" for anyone with a dark skin, DPA reported.
German police have stepped up patrols to ensure security in the capital as the final match of the World Cup soccer games, which will be held on July 9, is approaching.