Athens - Unknown assailants attacked five banks with petrol bombs and household gas canisters in the Athens suburb of Kalamaki overnight, Greek television reported Saturday morning.

An office of the ruling Nea Dimokratia party was also attacked, while a mobile telephone business was destroyed.

The attacks lasted only a few minutes, the television report said. There were no riots in Athens or other cities as had occurred in the previous week.

Shortly before midnight some 50 cyclists blocked the main road in front of the parliament building for 30 minutes and shouted chants against police brutality, the television report said.

The protest caused traffic problems in central Athens.

On Friday, some 400 students clashed with police in Athens.

The civil unrest erupted after police shot dead a 15-year-old boy on December 6. (dpa)