An explosive device wounded a police officer and a civilian when it detonated outside a church in central Athens police and state media said.
There was no claim of responsibility for the attack and no warning call that the device would go off, officials said.
The blast occurred outside the Saint Dionysios church around 7 a.m. local time (0500 GMT), just before it was due to open to the public for service.
The police officer and a second person – identified by state TV as the church caretaker – were taken to the hospital and police cordoned off the area.
Their injuries were not life-threatening, health officials said. At this time we declare peace and stability in the cities and nations of the world and the works of the enemy be thwarted and stopped, in the name of Jesus.