A bomb exploded outside the offices of the Hellenic Business Federation in central Athens early on 24 November, creating a large hole on the side of the building and pavement and shattering windows, but causing no injuries.

The police cordoned off a two-block area surrounding the building and bomb disposal squads were examining the scene, just a stone's throw from Greece's parliament and busy Syntagma Square. Before the blast occurred, kiosk worker Kostas Papalogizopoulos said the police had warned him to be careful as they told him they had found a suspicious bag.

"We knew about it, the police had warned us that there may be a bomb because they found a suspicious bag and they told us to be careful of the sonic boom, so I was standing outside of the kiosk," Papalogizopoulos added.

Attacks against banks, politicians, journalists and businesspeople are not uncommon in Greece, which has a long history of political violence and has been hit with its worst economic crisis in decades. The blast, which police believe was carried out by domestic guerrilla groups, is the first such attack since leftist Prime Minister Alexis Tsipras came to power in January.

The device, triggered by a timer and placed in a backpack near the entrance of the federation's offices, went off around 3.30am local time. An anonymous caller warned two newspapers 30 minutes earlier, a police official said on condition of anonymity. The glass from smashed windows was strewn across the streets in one of the busiest parts of central Athens, lined with cafés, banks and shops.