Violence erupted in Athens as thousands marched on parliament to demonstrate against the government's austerity plan.
Police used teargas as protests turned violent
Police fired tear gas at demonstrators hurling rocks and plastic bottles in central Athens as clashes broke out during a large protest march against government austerity measures on Wednesday.
The protest came as a 24-hour strike called by the largest private and public union groups threatened to paralyze the nation.
Transportation networks were hard hit as flights to and from Greece came to a halt at midnight. Ferries to the Greek islands and railway services were also affected.
"Today, Europe's eyes are turned on us, today we are demonstrating for hope and future ... to cancel the measures," Yannis Panagopoulos, head of the private sector union GSEE, told a rally of tens-of-thousands of protesters in Athens.
The city was covered in posters and flyers calling for Greeks to strike to the slogan "People and their needs above markets!"
The Athens metro and bus service were operating a skeleton service to allow striking workers to get to the demonstrations in the city centre.
Greeks are called on to join in the 24-hour nationwide stike
News blackout as journalists join strike
Employees in government ministries, municipal offices, banks, courts and hospitals were among those participating in the strike. Most schools and universities were closed.
Merchant shipping and hotels operated without any problem, however, as their personnel did not join in the strike.
It is the second major protest since Athens pledged to cut its deficit from 12.7 percent of gross domestic product (GDP) in 2009 to the three-percent limit prescribed by the EU by 2012.
Following pressure from EU member states and financial markets, public sector wages were frozen and salary allowances cut by 10 percent this year.
While the EU has pledged political support, it has also imposed strict deadlines and monitoring.
Experts from the European Commission, the European Central Bank and the International Monetary Fund arrived in Athens on Tuesday to assess the effectiveness of the Greek budget cuts.
Editor: Andreas Illmer