A bomb in a car exploded outside the Athens stock exchange on Wednesday, causing no casualties but slightly damaging the building and setting eight vehicles ablaze, Greek police said, Reuters reported.
They said a Greek newspaper had received a warning call before the explosion.
"It was an explosive device. The remains of it were found in a damaged car," said a police official.
"The blast was strong but damage to the building was minor. Eight cars are on fire," said the official.
Violence has struck Greece a number of times since the police shooting of a teenager in December.
The shooting sparked Greece's worst riots in decades and leftist and anarchist guerrilla groups have claimed responsibility for attacks.