Tens of thousands of people gathered in Turkey's largest city of Istanbul on Sunday to mark the International Workers' Day, also known as May Day, amid tight security measures.

This year, labor unions and city officials agreed to hold the rally in the remote district of Bakirkoy at Istanbul's European side, despite workers' insistence on gathering as past at the Taksim Square.

The square at the heart of the metropolis has been closed to all kinds of rallies since 2013.

At the rally, workers, labor union representatives, members of opposition parties and citizens mainly chanted against long working hours, low wages, discrimination against women and poverty.

Police fired tear gas at members of pro-Kurdish People's Democratic Party over a dispute due to attempts to carry out body checks for the second time.

Some members of leftist groups were dispersed by police with water cannons and tear gas, as they intended to break the police barricades to cross to the Taksim Square.

Meanwhile, 36 people in several parts of the city were arrested after they tried to march toward the square, official Anadolu Agency Anadolu reported.

Police have sealed off entire Taksim neighborhood with metal barricades, fearing that May Day rallies might turn into anti-government protests.

The metro station on the square has also been closed, with the owners of shops, bars, coffeehouses and restaurants in the area ordered to close their shops at midnight on Saturday till Sunday evening.

Amid the lingering threat of more terror attacks to come, some 24,500 security forces backed by helicopters have been put on duty, Istanbul governor's office said in a statement.

Unidentified gunmen opened fire on a May Day rally at the Taksim Square in 1977, killing 37 people and wounding hundreds of others.