At least eight shops, seven houses and two cars were damaged in the suburb of Maroussi in northern Athens, early on Thursday when an explosive device went off outside a Panathinaikos fan club, while several surrounding buildings suffered damages on their windows and walls.
Nobody was injured in the blast, which occurred at around 3.30 a.m. on Anavriton Street, but an elderly man in the neighbourhood suffering from heart problems was transferred to a hospital nearby as a precaution.
Police said that the attacker was riding on a large motorcycle and hurled an explosive device towards the fan club. The device probably contained dynamite and was not made up of camping gas canisters as is usually the case in such attacks.
The noise from the blast was heard in neighbouring districts, local residents said.
This is the third time that the same soccer fan club has been targeted, however this explosion was the most powerful.
Forensic police teams are combing the area for evidence that will point to the perpetrator, while footage from surrounding CCTV cameras has been collected.
Police is considering two possible scenarios: that the attackers were fans of an opposing soccer club or that they belong to a subgroup of fans from the same club who have unresolved differences with the main group.