May Day saw violent clashes between Turkish police and protesters who had been banned from gathering in Taksim Square in the centre of Istanbul, but tried to get there anyway.
Tear gas, water cannon and rubber pellets were met with petrol bombs, stones and fireworks as people repeatedly tried to breach police lines blocking the way to Taksim
There was also trouble in Kizilay Square in the capital, Ankara. Water cannon and tear gas was used there to disperse more than 1,000 demonstrators.
The centre of Ankara was on lockdown, with a heavy security presence and police helicopters buzzing overhead.
Citing security fears, the authorities had erected steel barricades and deployed tens of thousands of riot police in Istanbul.
Road blocks were set up and parts of the city’s public transport system were shut down to prevent people getting to Taksim which is a traditional rallying point for trade unions.
It was also the epicentre of weeks of anti-government protests last summer.
Euronews reporter Bora Bayraktar, who witnessed running battles in the streets, said: “There have been clashes going on here for hours in one of the streets which leads to Taksim Square and where a trade union office is located.”
One protester, who identified himself as a 37-year-old teacher and leftist activist, said: “This is a day of struggle. We’re not trying to reach Taksim to celebrate but to resist … We don’t want violence and whenever May Day was allowed in Taksim, it was peaceful.”
Around 100 people were reported to have been injured and at least 140 arrested.
Prime Minister Tayyip Erdogan has previously dismissed protesters as “riff-raff” and “terrorists”.
He sees last year’s street demonstrations and the corruption scandal that is dogging his government as part of a plot to undermine him.