Turkish police have used teargas and water cannon to disperse Labour Day protesters in Istanbul, with demonstrators shouting "Down with fascism" and "Long live May 1" as they tried to march toward the city's iconic Taksim Square.
As in previous years, authorities had banned Labour Day protests at the square, which had been cordoned off in the early hours.
Some 24,500 police had been deployed on Sunday, using 120 water cannon in the city, according to the official Anadolu news agency.
At least 40 people were arrested, it said.
The DHA news agency reported that a 57-year-old man was fatally injured when he was hit by a water cannon vehicle.
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Police helicopters had been circling over the city since the early hours.
The underground station at Taksim Square was closed and the Square itself was fenced off.
Trade unions called on the people not to rally at Taksim Square this year for security reasons, but to gather in an area outside the city centre, where public demonstrations were permitted.
The square is the site of the Monument of the Republic, which commemorates the republic's founding after the Turkish War of Independence in 1923.
On May 1, 1977, 34 people were killed in clashes at Taksim Square, prompting a ban on the use of the site by labour movements until 2010.
The ban was reinstated in 2013, and May Day activists that year clashed with police.
A month later, mass anti-government protests that had started in Taksim and the nearby Gezi Park spread to other cities.
