The trouble started at Wednesday's game between the Bucharest rivals when three Dinamo fans posed as officials and crossed into Steaua's section to steal a banner. Police used water cannons, rubber bullets and tear gas to disperse the mostly Steau fans in the stands and near the Dinamo stadium.

Romanian TV station Realitatea reported 28 fans needed treatment in hospital.

Police said Thursday although the fans had tried to enter the pitch, some officers had used unnecessary force. Six policemen were injured in the clashes.

Dinamo won 1-0 and leads the league with 24 points, followed by CFR Cluj with 19 and Steaua with 17.