Tens of thousands of Greeks have taken to the streets in the country's second general strike in a month against newly proposed austerity measures.
Thursday's protests saw hundreds of youths pelting riot police with petrol bombs, bottles and chunks of marble.
Al Jazeera's Dominic Kane quoted demonstrators in Athens as accusing the European Union of being the problem and saying: "We can't take this, enough is enough!"
The measures for 2013-14, worth $17.7bn, aim to prevent the country from going bankrupt and potentially having to leave the 17-nation eurozone.
Riot police responded with volleys of tear gas and stun grenades as protesters ran from the area of clashes in the capital's Syntagma Square outside parliament, splitting the demonstration in two.
Heavy police deployment
Hundreds of police were deployed in Athens in the run-up to the demonstration, as such protests have turned violent in the past.
"The 24-hour strike accompanying the protests was meant to send a message to the EU, to Merkel, Hollande ... to send them the message that they could only push Greece so far. That was a refrain I heard several times from the people I spoke to," our correspondent said.
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The strike grounded flights, shut down public services, closed schools, hospitals and shops and hampered public transport in the capital.
Taxi drivers joined in for nine hours, while a three-hour work stoppage by air traffic controllers led to flight cancellations. Islands were left cut off as ferries stayed in ports.
"A poll tonight puts Syriza ahead of the conservative-led governing coalition and it puts the far-right Golden Dawn at 14 per cent. If that's true, it poses a serious problem for the government," Al Jazeera's Kane said.
"Now whether you can draw a link between the popularity of Golden Dawn and the anarchists and the splinter groups throwing rocks and petrol bombs, is another matter. But it certainly exposes the popular disaffection with government here and indeed the disaffection with the EU."
A protest march by about 17,000 people in the northern city of Thessaloniki ended peacefully.
Athens has seen hundreds of anti-austerity protests over the past three years, since Greece revealed it had been misreporting its public finance figures.
Thursday's strike was timed to coincide with a European Union summit in Brussels later in the day, at which Greece's economic fate will likely be a major topic of discussion.
The heads of the 27 EU member states are in the Belgian capital to discuss how to save the euro from collapse and support countries facing too much debt and not enough growth.
But Thursday and Friday's summit promises to be just a small pit-stop on the road to recovery, with few decisions expected. The discussion will also include ideas of how to support the nations' banks, one part of the crisis.
Some countries have stepped in to save their failing banks, and are now struggling themselves. The EU is considering forming a "banking union" to break this dangerous connection. But some countries are eager to put on the brakes on the plan.
Whether to give Europe's bailout fund the power to lend money to banks will be at the centre of the debate.
The discussion will have an impact on an ongoing rally in the European stock market, which staggered higher early on Thursday.
The FTSEurofirst opened up 0.06 points at 1,118.68, nearing the highs of around 1,121 reached after the European Central Bank announced its bond-buying plans at the end of August.
"We are close to the top of the current range. We could edge higher if Spain asks for assistance from the European Central Bank, but any gains will likely be short-lived as investors focus on company earnings," Heinz-Gerd Sonnenschein, equity markets strategist at Deutsche Postbank in Bonn, said.