Turkish police on Sunday clamped down on unauthorised protests during a tense May Day in Istanbul, using tear gas and water cannon against demonstrators and imposing a heavy security blanket on the city.
In a separate incident, a man was killed when he was run over by a police water cannon vehicle.
The authorities prevented all public access to Taksim Square in the centre of the city -- the traditional focus for protests -- and the usually bustling area was deserted save for police.
Hundreds of labour and union activists, brandishing slogans promoting workers' solidarity, took part in an officially-sanctioned action at a vast market ground in the outlying district of Bakirkoy close to the international airport.
However police used tear gas against members of the pro-Kurdish Peoples Democratic Party (HDP) who sought to stage a protest of their own in Bakirkoy, roughly arresting several people, an AFP photographer said.
Police also used water cannon and tear gas on protesters in the district of Sisli who were trying to march on Taksim, another AFP photographer said.
The state-run Anatolia news agency said 36 people were detained in Sisli and the neighbouring district of Besiktas as they tried to march on Taksim, reports said.
The man who was killed was run over by a police water cannon vehicle, known by its Turkish acronym TOMA and which have become ubiquitous in recent years as the police crack down on protests.
The man, 57, was knocked down by the TOMA while trying to cross the Tarlabasi Street close to Taksim,, reports said. An investigation has been opened.
Access to Taksim, the main hub in the European side of the city, was cut off by an interlocking network of police barriers. The square, usually filled with hundreds of people, was completely empty save for a few police.
The Istanbul governor's office had said 24,500 members of the Turkish security forces would be on duty in the city on Sunday "to provide for the security of citizens".
May Day comes at a time of particular tension in Turkey after a succession of deadly attacks this year blamed on jihadists and Kurdish militants.
Two police were killed and 22 other people wounded Sunday in a car bomb attack in the city of Gaziantep close to the Syrian border.
Meanwhile, Turkish police detained four suspected Islamic State jihadists who were allegedly planning an attack on May Day celebrations in the capital Ankara, the state-run Anatolia news agency said.