A powerful bomb wrecked a Greek bank in the outskirts of Athens early on Tuesday, damaging nearby cars and blowing out windows across the street but causing no injuries, police said.

The bombing, outside the Greek Eurobank in the southeastern Argyroupoli district, was the latest of several attacks in the Greek capital in the months following the police killing of a teenager in December.

"We believe it is a terrorist attack. The anti-terrorism squad is investigating the remnants of the bomb and the area," said a police source.

Police said a patrol car had spotted two men wearing helmets in the early hours of Tuesday outside of the bank ahead of the explosion but they drove away when accosted by the officers.

"When the policemen approached, one of the men threatened them with a gun after jumping on a motorcycle with his accomplice," a police statement said.

The police saw broken glass and a black bag inside the bank, and cordonned off the area. An anonymous caller warned a Greek newspaper that a bomb would explode within 30 minutes.

"No one has been injured but there is significant material damage," the police said. The bomb exploded at 0405 local time (0105 GMT), they said.

Greece has suffered a string of anarchist and leftist bombing and arson attacks aimed at domestic and foreign firms, including several banks, since December's widespread rioting.

"We are waiting for test results to see whether the explosive material used could identify a group that might have struck before," police spokesman Panagiotis Stathis told Reuters.

One of Greece's militant guerrilla groups Revolutionary Struggle claimed responsibility in March for two bomb attacks against Citibank branches in Athens.