A bomb exploded outside the offices of JP Morgan in Athens, causing extensive damage to the entrance of the building but no injuries, reports said on Tuesday.
An unknown caller to the Greek newspaper Eleftherotypia warned of the bomb minutes before it went off in the upscale Athens district of Kolonaki where JP Morgan's Greek offices are located.
Police and sniffer dogs had cordoned off much of central Athens, including the parliament building.
Reports said the explosion was caused by a time-bomb, which ended up smashing the entrance to the building.
No group has claimed responsibility for the attack but officials believe that it could be the work of an anarchist group protesting the government's recent austere economic measures.
Banks, government buildings and diplomatic missions are targets for a spade of bomb attacks in the past few years since the police shooting of a teenager in December 2008.