Police and demonstrators have clashed in Athens over government austerity measures.
At least 17 people were injured, one critically, when tear gas and stun grenades were used to disperse youths hurling stones and petrol bombs.
Police said there were several arrests and that two officers were hurt.
The BBC reports the clashes happened close to a meeting by Finance Minister George Papaconstantinou with EU and International Monetary Fund officials.
The march was part of a 24-hour strike that has halted public services and paralysed transport networks in Greece.
At least 20,000 people marched through the capital and another 8000 protested in the northern city of Thessaloniki.
The strike was called by unions after the Greek government proposed a new austerity package to try to reduce the budget deficit and ease the country's crippling debt crisis.
But unions say the policies are making Greece's problems worse.
An EU mission is in Athens this week to review Greece's progress on meeting the terms of an emergency bail-out worth 110 billion euros ($US158 billion) by the EU and IMF last year.
The BBC reports there is speculation that the government may need a further international loan.