Police and protesters have clashed in Istanbul after hundreds tried to breach barricades and reach the city's main square to mark May Day in defiance of a government ban.
Some demonstrators hurled stones, petrol bombs and fireworks at riot police, who responded with tear gas as clashes broke out on side streets leading to Taksim Square.
The square is the city's main hub and is currently undergoing a major facelift. The Turkish government banned celebrations at Taksim this year, citing construction safety risks.
Trade union groups, however, have vowed to mark May Day in Taksim, which is of symbolic importance to workers and left-wing groups. Dozens of protesters were killed there in 1977 when unidentified gunmen opened fire on May Day celebrators.
Subway, bus and ferry services across the Bosporus were partially suspended and bridges were closed down to prevent large groups from gathering in Taksim. Some 22,000 officers were deployed to police the city.
Throngs of demonstrators, waving flags and shouting anti-government slogans, still tried to access the square.
Meanwhile ferry and train services in Greece ground to a halt as unions held a strike for May Day. Hundreds joined rallies in central Athens to mark the day.
The country's main unions are protesting over soaring unemployment, which is the highest in the 27-country European Union, and the austerity measures the government is enacting in return for crucial bailout loans.
Greece nearly went bankrupt in 2010 and has since depended on money from its eurozone partners and the International Monetary Fund, granted on condition the government pursues deep spending cuts and wide-ranging economic reforms.
While the austerity has succeeded in reducing high budget deficits, it has been at a huge cost, with the country in its sixth year of deep recession.