A bomb hidden on a parked motorcycle has exploded outside two court buildings in central Athens, damaging cars and shattering windows but leaving no one hurt.
The powerful rush-hour blast occurred at 8.20am today following a warning telephone call to a newspaper and private TV station, authorities said.
Police had evacuated the targeted buildings, which are used for administrative purposes. State health officials confirmed that no one was injured.
There was no immediate claim of responsibility, but suspicion fell on Greek militant groups, which have stepped up attacks in the past two years. A group of suspects are facing trial next month.
The blast occurred in a densely populated area in the city's Ambelokipi district, shattering windows and nearby shopfronts, and damaging cars. It sent up a cloud of smoke that was visible across the city.
At least a dozen suspected members of the violent anarchist group calling itself Conspiracy Nuclei of Fire are due to go on trial on January 17.
The group also claimed responsibility for a spate of parcel bomb attacks targeting embassies in Athens and other sites in November.
A violent Italian anarchist group carried out a string of embassy bombings in the past week, in solidarity with jailed Greek militants.
Attacks by far-left and anarchist militant groups jumped by 43pc in 2009 in the European Union compared to the previous year, according to the EU police agency, Europol, with most of the incidents in Italy, Spain and Greece.