Greek authorities launched a ban on paper tickets for all league soccer matches on Tuesday as part of an effort to crack down on the violence that has plagued the sport for decades.

Under new rules, fans will only be allowed into stadiums using their cellphones and displaying a government-issued QR code so they can be identified and attendance bans can be enforced.

Stadiums have been closed to spectators for two months so security measures could be overhauled following the death of a police officer who was hit by a flare during a fan riot in Athens in December.

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Starting Tuesday, fans will have to buy tickets online and verify the purchase using a state-run app used to pay taxes and access online government services.

Dimitris Papastergiou, a minister for digital governance, said the full paper ticket phase out would last one month. Exceptions, he said, would be made for minors and seniors, adding that the new system would be expanded to other sporting events after the summer.

"The goal is also … to relieve the Greek police of the need to provide hundreds of policemen at stadiums. Police will not be needed at stadium entrances," Papastergiou told state-run ERT television.

The minister said 10,000 of the current 80,000 season-ticket holders had already switched to the new electronic system.