Turkey May Day protests hit by tear gas near Taksim Square
Riot police in Turkey have used tear gas and water cannon to prevent demonstrators defying a ban on protests on Istanbul's central Taksim Square.
The Anadolu news agency said several demonstrators were injured and at least five detained.
Intensive security measures were in place, and roads and streets near Taksim Square closed to traffic from the early morning.
Turkish media said some 40,000 police would be deployed in the city on 1 May.
At the scene
In Besiktas, a district of Istanbul 15 minutes away from Taksim Square, protesters started gathering early in the morning. So did the police.
The first intervention with tear gas and water cannon came around 08:00 local time and the scuffles between the police and protesters went on non-stop for almost five hours.
Some protesters used slingshots on police, some broke pavements to make ammunition. Other protesters apparently opposed this, fearing it would provoke the police and lead to heavier intervention.
The smell of tear gas was always in the air but people were determined to stay nevertheless. In between police interventions they would dance, sing and chant anti-government slogans.
One protester told me they would try making their way to Taksim Square no matter what the cost.
Prime Minister Recep Tayyip Erdogan earlier warned people they should "give up hopes" of gathering on Taksim Square - a focus of anti-government protests.
But a joint statement from the main trades unions on Wednesday said: "We will be in Taksim despite the irrational and illegal ban. All roads will lead to Taksim on May Day".
Mr Erdogan's party won local elections in March. That was the first vote since mass protests last June, and was seen as a barometer of his popularity.
The prime minister has been eyeing a run for the presidency in August - the first time voters will directly elect the head of state - or may seek to change the rules to allow him to seek a fourth term in office.
Elsewhere in May Day celebrations:
- A number of people are reported to have been beaten by security forces in Cambodia who were trying to break up an opposition march in the capital Phnom Penh
- More than 100,000 Russians have taken part in a parade in Moscow's Red Square, reviving a tradition last seen before the collapse of the Soviet Union in 1991.