Authorities in Serbia say at least 50 people have been injured and 41 arrested after fierce clashes involving fans of rival Belgrade soccer clubs Red Star and Partizan.
The violence erupted before a match between the two teams in the capital on April 25.
The match was postponed for 40 minutes when fans attacked each other with sticks and stones.
Red Star supporters also threw seats and flares at riot police.
The match, which eventually ended in a scoreless tie, was halted for seven minutes when flares were thrown onto the field.
The Serbian Interior Ministry said that "hooligan behavior has led to slight injuries to 35 police officers."
It said that police had arrested 41 people and turned back a van from the northern city of Zrenjanin that was "loaded with rocks and bricks."