Greek students clashed with police in central Athens during a protest which turned violent on Monday.
Police fired tear gas on rioting teenagers who attacked them with petrol bombs and stones.
No arrests or injuries were reported from the clashes, which started outside the Greek parliament at Syntagma Square and continued outside the ancient site of the Temple of Olympian Zeus.
Police said some 2,000 people took part in the protest against the government’s education policies.
Reforms wanted by the education ministry include curriculum changes in the final year of high school, however, students say the changes will increase the stress of exams.
Reports claim most of the trouble was caused by hundreds of youths wearing masks who vandalised cars, traffic lights, public phones and other public property around the centre of Athens.