The crackdown comes after years of clashes between ultras and police forces, but fans blame the government for failing to address "a deep social problem".
ADVERTISEMENTGreece has introduced emergency legislation to ban all fans from its top football tournament, the Super League.
Athens announced the crackdown after the hospitalisation in a coma of a young police officer on Thursday.
The man was hit by a flare during clashes between Olympiacos and Panathinaikos hooligans in the Rentis area of the capital, suffering extensive bleeding and cardiac arrest.
As a result, all games due to take place last weekend were postponed.
The all-out ban will last at least two months
The measure takes immediate effect to stay in place until February 12, but the government didn't rule out an extension.
The ban also involves Super League clubs fielding "cadet" teams in the lower-rank Super League 2, i.e. AEK Athens B and Paok B.
Upon announcing the measures, government spokesman Pavlos Marinakis painted a worrying picture of Greek football.
The latest "murderous attack against a policeman is not the first incident of extreme fan violence in recent years. Criminals in the guise of sports fans are committing serious offences, seriously injuring and killing people".
New measures to beef up stadium security and surveillance
All the clubs competing in the Super League will also have to install surveillance cameras inside stadiums and use personalised ticketing systems that require holders to show identification upon entry.
The security systems, including a network of high-resolution surveillance cameras inside stadiums, would have to adhere to standards set by UEFA, Europe's football governing body.
'Stripped of our rights!': Fans protest the government's move
Violence has plagued Greek football for decades despite repeated efforts to crack down on the supporters’ associations blamed for the attacks.
But the latest ban is already proving hard to swallow for the fans, who are accusing the government of pointing the finger at them instead of fixing its "failures" and addressing a "deep social problem".
Many are also demanding a refund for the games they won't be able to watch, however that's highly unlikely to happen given current closed-door regulations, which bear no liability for the clubs in case the decision depends on fan violence.
Meanwhile, an 18-year-old man has been arrested and taken into police custody in connection with the police officer’s injury, to face charges of attempted murder.
The man, who hasn't been identified, appeared at an arraignment hearing Monday after being escorted to court in handcuffs. He was given until Thursday to prepare his defense.