A large car bomb was defused outside another Citibank branch in February
A bomb has exploded behind a bank in Athens, damaging two cars but causing no injuries, Greek police have said.
The explosion happened outside a branch of Citibank at 0300 (0100 GMT) in the Nea Ionia district of the capital.
Police said the bomb was detonated from close by using electric cables. There has been no claim of responsibility.
Last month, a car bomb was defused outside another Citibank branch. No arrests have yet been made, but police suspect a left-wing militant group.
A police spokeswoman told the Associated Press that "a medium-sized improvised device" had been used in Monday's attack.
The bombing came amid a campaign of violence by far-left militants, such as Revolutionary Struggle and the previously unknown Sect of Revolutionaries, who have mounted several attacks on police and government officials in recent months.
Greece has faced severe anti-government protests and rioting since police shot dead a teenager in December.