Trouble erupted as a group of protesters tried to storm the Greek parliament
Protests in Athens have turned violent amid a general strike over planned austerity measures that has brought the country to a standstill.
Petrol bombs have been thrown at police who responded with pepper spray, tear gas and stun grenades.
A building in the city has also been set on fire and people are being evacuated, reports say.
Protesters are angered by spending cuts and tax rises planned in return for a 110bn euro (£95bn) bail-out for Greece.
Parliament is to vote on the measures by the end of the week.
Measures include wage freezes, pension cuts and tax rises. They aim to achieve fresh budget cuts of 30bn euros over three years, with the goal of cutting Greece's public deficit to less than 3% of GDP by 2014. It currently stands at 13.6%.
A mass rally attended by thousands of people took place in central Athens before some protests began to turn violent
Outside parliament, a group of protesters rushed up a flight of steps, taunting MPs to come out and calling them "thieves".
Riot police forced them back with pepper spray, tear gas and stun grenades.