A group of anarchists that had infiltrated a student demonstration in Athens caused extensive damage to a number of shops and banks in the centre of the city.
Police forces used tear gas at Syntagma Square to push back the anarchists who were throwing petrol bombs, bricks and rocks.
There is no information of any arrests made.
The violent scenes followed a protest by students against the education policy and undefunding for schools.
Thousands marched in the center of the Greek capital demanding more funds for education.