Police in Athens on Wednesday clashed with hooded youths throwing firebombs on the sidelines of a large demonstration against a new round of austerity cuts.
Officers fired tear gas and stun grenades to disperse a group of 50 protesters near luxury hotels in the capital's central Syntagma Square, as tens of thousands protested in Athens and Thessaloniki.
The youths also smashed window fronts and set fire to garbage on the square.
The incidents occurred during a general strike, the third this year but the first to test the resolve of the coalition government that took office in June
Some 34,000 people have turned out to demonstrate in Athens and another 18,000 in Thessaloniki against the new cuts, according to police.
The government is trying to finalise a package of some 11.5 billion euros ($15 billion) in extra cuts.
Another two billion euros must be raised from taxes under the austerity measures due to be introduced to parliament in early October by the three-party coalition headed by conservative Prime Minister Antonis Samaras.