Bomb explodes in central Athens (PHOTOS)

A bomb exploded outside the offices of a Greek business federation in one of the busiest parts of Athens early on Tuesday, smashing windows but causing no injuries, police officials said, according to Reuters.

The device, triggered by a timer and placed in a backpack near the entrance of the Hellenic Business Federation offices went off around 03:30 local time (01:30 GMT). An anonymous caller warned a newspaper some 30 minutes earlier, a police official said on condition of anonymity.

Attacks against banks, politicians, journalists and businesspeople are not uncommon in Greece, which has a long history of political violence and has been mired in its worst economic crisis in decades.

Tuesday's 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 blast scene is just a stone's throw from parliament in Syntagma Square that is lined with cafes, banks and shops.

Police cordoned off a two-block area surrounding the building and bomb disposal squads were examining the scene.

Makeshift bomb and arson attacks have escalated in Greece since 2010, when it first adopted unpopular austerity measures such as tax rises, wage and pension cuts in exchange for multi-billion euro bailouts by the European Union and the IMF.

In July, Athens agreed to further rounds of austerity under its third bailout.