Hooded protesters threw petrol bombs and set off fireworks during clashes with Greek riot police in Athens on Tuesday (local time) on the eighth anniversary of a teenager's killing by police.
The fatal shooting of 15-year-old Alexandros Grigoropoulos in 2008, a year before Greece's economic crisis began, triggered the worst riots seen in Greece for decades and they lasted for weeks.
The annual march to commemorate the incident usually draws thousands of anti-establishment and anti-austerity protesters.
Tuesday's violence erupted after hundreds marched peacefully in Athens.
Small fires burned in the streets of the district in central Athens where the shooting took place. Demonstrators hurled scores of petrol bombs and rocks at police in riot gear, who responded with tear gas.
Greece is in its eighth year of recession and its economy is struggling with record high unemployment. It has called on its international lenders to abandon demands for harsher austerity once the latest bailout - the third since 2010 - ends in 2018.
