A bomb exploded outside a Greek ministry in Athens late on Friday, causing material damage but no injuries, a police source said.

The bomb went off outside the Greek secretariat for information shortly before midnight, after private television stations Alter and Antenna had received anonymous warnings by telephone that an explosion was imminent.

Police were given about 12 minutes to clear the area, the source told AFP .

The blast smashed windows at the ministry, state television NET said.

The incident is the second targeting a Greek state building in a week.

Last Saturday, an explosive device went off in a rubbish bin outside the Greek parliament without injuring anyone.

Attacks against political, economic interests

The parliament attack was claimed by a far-left organisation calling itself Conspiracy of Fire Nuclei, which has carried out a string of arson strikes against the homes and offices of politicians in recent months.

The group also claimed a bombing that caused extensive damage to the ground floor of Greece's largest insurance company Ethniki Asfalistiki on December 27.

"We aim to cause material damage and we point out to the police that it should evacuate areas in a timely fashion," a text claiming the insurance building attack on behalf of the outfit said at the time.

Greece has been rocked by attacks against economic interests and political targets since a youth was killed by a police officer in December 2008.

Another group, Revolutionary Struggle (EA), has been active for the last six years and is blacklisted by the European Union as a terrorist organisation.

EA claimed an attack on the Athens stock exchange in September which caused no injuries. In 2007 the group had fired a rocket at the American embassy without hurting anyone.

- AFP