Police clashed with demonstrators in central Athens as thousands attended rallies to mark the fifth anniversary of a fatal police shooting of a teenager - a killing that triggered major riots in Greek cities for three weeks.
Police said four officers were injured in the clashes on Friday, 10 people were arrested for causing public disturbances and 55 people were detained for questioning.
Several hundred youths hurled rocks and petrol bombs at police, burned two cars and set fire to piles of garbage, after about 5,000 protesters held two separate marches.
Police used tear gas, pepper spray and stun grenades against the rioters.
Alexis Grigoropoulos, 15, was killed the night of Dec. 6, 2008, when a policeman fired his gun following an argument in the centre of the capital.
Within hours of the boy's death, thousands of youths took to the streets across the country. The riots that ensued were Greece's worst in decades and buildings and shops on major streets were burned and looted in the capital.
The riots occurred a year before Greece was plunged into a financial crisis, and protesters at anniversary events often have opposed the government and the "troika" of bailout inspectors from the European Union, the European Central Bank and the International Monetary Fund.
Police remained on alert in several cities across Greece, including Athens, where more protests were expected Friday night.
In Thessaloniki, Greece's second largest city, demonstrations coincided with the funeral service for a 13-year-old Serbian girl - known only by her first name, Sara - who was found dead over the weekend.
That happened after her unemployed mother used a barbecue grill to try and heat their home, which had had its electricity supply disconnected.
A coroner said the girl had died of carbon monoxide poisoning.
Protesters gathered outside the church where the service was held, and chanted: "They killed little Sara. This is what the troika means."
