Greek police found and later detonated an explosive device that had been left outside the labour ministry in central Athens on Monday, police sources said, after a newspaper was tipped off that a bomb had been planted.
Police found the device in a rucksack propped up against the shutters of the ministry, on a central thoroughfare in Athens.
It was one of three suspect packages that police examined on the scene and then destroyed in controlled blasts.
Earlier, a telephone call to a Greek newspaper had warned that a blast outside the ministry was imminent.
There was no claim of responsibility for the incident.
Such attacks are not uncommon in Greece, which has a long history of political violence. Small-scale attacks have escalated since 2010, when the government first adopted unpopular austerity measures in exchange for multi-billion-euro bailouts from the European Union and the IMF.