A Greek guerrilla group claimed responsibility for a time bomb that exploded outside the Athens home of a prison director on Friday, slightly wounding one woman in the face, police officials said on Saturday.
The Conspiracy of Fire Cells said it planted the device, which police estimate contained at least 1 kg of dynamite, under a car used by the director of the high-security Korydallos prison in the Dafni neighborhood of Athens.
An unidentified caller had warned a news website on Friday that a bomb would go off in 20 minutes. The prison director was unharmed.
"After almost two years of silence, the bomb we placed at the Korydallos prison director's car is the first drop before the storm," the group said. "It is a show of solidarity for our 10 imprisoned brothers."
The jailed group members are on trial, charged with a series of bomb and gas canister attacks.
Police believe the claim, which was posted on a website, to be authentic. "The group could strike again against judicial or police targets," said a police official, who spoke on condition of anonymity.
Small homemade bomb attacks by militant groups are frequent in Greece and usually target police, public buildings or businesses.
Attacks on political figures and journalists have picked up in recent months, some claimed by anti-establishment leftists angry about Greece's financial woes.
The Conspiracy of Fire Cells has carried out parcel-bomb attacks against embassies and foreign governments, according to police, who have arrested dozens of suspected group members since November 2010.
In January, two Greek anarchist groups claimed responsibility for an explosion at an Athens shopping centre that fuelled fears of rising political violence.