Athens  - A bomb exploded outside a Citibank branch in Athens on Monday, causing damage but no injuries, Greek news reports said.

Reports said the bomb went off behind the building in the Athens suburb of Filothei.

No group claimed responsibility for the attack, but police believe far-left militant groups to be behind the bombing.

It would the second time that militant leftists targeted Citibank.

Last month, police managed to defuse a car bomb that contained hundreds of kilograms of explosives.

The blast followed a spate of gun and arson attacks across the city by suspected militant groups against police following a police shooting of a 15-year-old boy in December.

The shooting of the teenager triggered Greece's worst riots in decades. (dpa)