Police have clashed with protesters hurling petrol bombs in central Athens after an anti-government rally called as part of a general strike turned violent.
Riot police used tear gas and pepper spray against several hundred demonstrators after the violence broke out near the country's parliament. Protesters also set fire to trees in the National Gardens and used hammers to smash paving stones and marble panels to use as missiles against the riot police.
About 50,000 people joined the union-organised march in central Athens, held during a general strike against new austerity measures planned in the crisis-hit country. The action, the first large-scale walk-out since the country's coalition government was formed in June, closed schools and disrupted flights and most services.
Everyone from shopkeepers and pharmacists to teachers, customs workers and car mechanics joined the demonstration, seen as a test of public tolerance for more hardship after two years of harsh spending cuts and tax hikes.
"People, fight, they're drinking your blood," protesters chanted as they banged drums.
As the strike got under way Greece's prime minister and finance minister hammered out a new package of spending cuts demanded by the country's international lenders.
Greece's politicians have struggled to come up with more austerity measures that would be acceptable to its rescue creditors, with disagreements arising between the three parties that make up the coalition government. The country has been dependent on international loans from other eurozone countries and the International Monetary Fund since mid-2010. Without them, Greece would be forced into a chaotic default on its debts and possibly into an exit from the euro.
The country's lenders have demanded more fiscal reforms if they are to continue issuing more rescue payouts.
The strike shut down the Acropolis, Greece's most famous tourist site, and halted flights for hours. Ferry services were suspended, schools, shops and service stations were closed and hospitals were functioning on emergency staff.
One of those striking was Athens hospital worker Alkis Betses, who has seen his salary fall from 1,300 euros (£1,033) to 800 euros (£636) a month, said new cuts will bring it down to 600 euros (£477).
"How can you survive on 600 a month, with ever-rising taxes, and continue to pay bills and buy necessary supplies? If the washing machine breaks down, where do you get the money for repairs?"
Mr Betses said hospitals have been hard hit by spending cuts, with staff shortages and long delays in doctors' overtime pay for night shifts.
"The resentment has been there for long before the new measures. Imagine what will happen when they're made public," he said.