ATHENS, Jan. 20 (Xinhua) -- Unidentified people made two false calls warning of an impending explosion at a soccer stadium at the port city of Piraeus on Sunday evening, a few hours after a bomb attack at an Athens shopping mall caused two injuries.
The unidentified persons warned that a bomb would explode during a match for the Greek Cup.
Similar warning calls had been made before the blast at the shopping mall on Sunday noon which had been evacuated in time. It was the first time ever such an attack hit a popular shopping centre in Greece.
Police experts on Sunday evening investigated the crowded stadium and evaluated that there was no real threat, therefore it was not evacuated.
In the meantime, counter-terrorism squads continue the investigation to track down the perpetrators of the attack inside the northern Athens suburb mall.
According to a police statement, the small power makeshift explosive device was made with gunpowder in a pressure cooker which was placed near a bank branch on the building's first floor.
No group or individual has claimed yet responsibility for the blast, which comes after a series of gunfire and petrol bomb attacks at the ruling conservative party headquarters on Monday, journalists' homes and the Greek government brother's house over the past two weeks.
Counter-terrorism experts speaking anonymously to media note that the methodology reminds of previous attacks by the "Conspiracy of the Nuclei of Fire."
The local guerilla group since 2008 has been linked with firebombings at police, political and business targets and the parcel bomb thriller targeting European leaders and foreign embassies in November 2011.
In an interview with a local daily, Greek Citizen's Protection Ministrer in charge of public order Nikos Dendias said that the authorities had some indications since last November that domestic terrorists were preparing attacks.
Greece has suffered from domestic terrorism over the past four decades and after the start of the debt crisis in 2009 which has led the country to the brink of bankruptcy, dramatically eroding living standards, several groups have linked attacks with the harsh austerity measures implemented to resolve the crisis.