The Greek league game between leader Olympiakos and Panathinaikos was abandoned with eight minutes to go on Sunday because of escalating clashes between fans and the police.
Police announced that 57 people had been detained and a further 20 arrested, while nine police officers were injured, two of them seriously.
"We dedicated several thousand personnel to policing the game and we faced, beginning two hours before the game started, escalating attacks,» police spokesman Athanassios Kokalakis said.
Olympiakos, four points ahead of Panathinaikos before the game, was leading 1-0 from Djamel Abdoun's 51st-minute goal.
No Olympiakos fans attended the game at Olympic Stadium in accordance with a league policy not to allow visiting fans due to fears of violence.
Sports general secretary Panos Bitsaxis said on television that the state had taken «the best possible security measures» and accused football clubs of doing nothing to curb the fanatical supporters and of opposing the state's attempts to impose tougher sanctions. Bitsaxis left open the option of postponing the next round.
According to league rules, Panathinaikos is facing having three points deducted and a steep fine, up to €180,000, and could play several games in front of empty stands. Up to two points could also be deducted from the following season.
Clashes between police and fans started before the game, when hundreds of youths without tickets tried to enter the stadium. The conflict continued throughout, forcing the second half to start 35 minutes late.
A group of about 200 hooded individuals were seated in a VIP section, next to the players' tunnel. Some of them carried clubs and iron bars. They were confronted by a line of riot police on the other side of a trough, who they attacked at halftime.
At one stage, about 30 of the hooded hooligans isolated two policemen and attacked them with clubs and bars. The beating went on for about five minutes before another detachment of riot police came to their colleagues' rescue.
In the second half, Panathinaikos fans set fire to seats in the upper and lower decks. Referee Tassos Kakos abandoned the game when firebombs were added to the mix of projectiles thrown at police and photographers.
The firebombs — which were also thrown at police outside the stadium — were water bottles filled with gasoline, liquid ammonia and little sticks of dynamite.
"The noise was so much that the players could not concentrate,» Olympiakos coach Ernesto Valverde said.
The stadium's electronic scoreboard caught fire and was damaged. Fire trucks entered the stadium's track to put out the fires but were attacked by fans, so trucks with water cannons were used instead. The fires were eventually put out.
"We had been cooperating with the police for almost a month in preparation for the game,» league general manager Michalis Anagnostou said. «The result was not what we wished for.»
Broadcaster NovaSports did not show any of the images of exploding firebombs, instead focusing entirely on the match.
Owner Forthnet Group released a statement saying they «will continue to isolate violent scenes and any message irrelevant to football.» [AP]