The man, an AEK fan, was stabbed several times during the clashes outside AEK's football pitch in Nea Philadelphia late on Monday, a police official said.

Police said 100 to 120 Dinamo Zagreb fans showed up late on Monday near the stadium, where AEK fans had gathered.

Clashes broke out more than an hour after the visiting team's training session ended and the team had left the stadium, with fans from both sides hurling flares, makeshift explosives and stones, police said.

Three Greek and five Croatian fans were also injured and being treated, and 98 people were arrested for taking part in the violence, the police official said.

Greek soccer has been plagued by violence on and off the pitch and authorities have repeatedly promised to clean up the game.

Fights between football fans are frequent before or after a game despite heavy fines. Α 19-year-old soccer fan, Alkis Kampanos, was beaten and stabbed to death outside the Aris Thessaloniki club stadium in the northern city of Thessaloniki last year.

Dinamo condemned Monday's incident.

"Such events are not in line with the values ​​and ethics we promote as a club and community," the team said in a statement on their website on Tuesday.

The UEFA Champions League qualifying-round match between AEK and visiting Dinamo Zagreb that was scheduled to take place at AEK's stadium on Tuesday was postponed as the conditions for the match were not met, UEFA said in a statement.

"Violence has no place in our sport and we expect that those responsible for this terrible act be arrested and consigned to justice in the shortest delay," it said.

UEFA confirmed later on Tuesday that the match had been rescheduled to August 19th.

Greek citizen protection minister Giannis Oikonomou said on Tuesday the state needs to intensify efforts to curb sports violence and that it was "unacceptable" that police had to failed to prevent the incident.

Seven police officers will be dismissed from their posts as a result, he said.