Police were studying CCTV footage last night for clues on a suspected terrorist bomb attack on the Labor Ministry in central Athens yesterday. Nobody was hurt by the bomb, which was the most powerful to explode in Greece in recent years. The device was made of dynamite linked to an alarm clock, battery and detonator. It was discovered at 2.30 a.m. outside the ministry – a few hundred meters from Omonia Square – by a vagrant rummaging through garbage. The device had been placed in a rucksack among rubbish a few meters from the entrance to the ministry. The area was cordoned off within minutes. A male caller then contacted Eleftherotypia daily newspaper at 2.40 a.m. to warn the bomb would explode shortly, without identifying himself as belonging to any specific terrorist group. The explosion came 13 minutes later, shattering the windows of every building in a 100-meter radius. But nobody was hurt by the blast. The government condemned the attack. The explosion was so powerful that few remnants of the bomb were left to provide authorities with clues. Police were examining witness statements and CCTV footage after some people said they had seen a young man leave a rucksack outside the ministry. This was the 10th bomb to go off since 2002, when a string of November 17 left-wing terrorists were arrested. The Revolutionary Popular Struggle (ELA) group was broken a year later. Sources said police are attributing it to one of the organizations which have been active since 2003, such as Revolutionary Struggle, which claimed responsibility for the bombing of a police station in Kallithea 100 days before the start of last year’s Olympics.