Turkish police used water canon and tear gas on Thursday to disperse thousands of protesters who tried to defy a Labour Day ban on demonstrations on Istanbul's Taksim Square, the scene of protests that have dogged the government for months.
After giving a final warning, hundreds of riot police backed by water cannon moved in on the protesters in the Besiktas district as they tried to breach the barricades leading up to the symbolic square, according to an AFP reporter.
They then fired tear gas and water cannon at the protesters, with smoke rising above the district that is home to Prime Minister Recep Tayyip Erdogan's office.
A reported 40,000 police officers as well as dozens of water cannon trucks and armoured vehicles were deployed throughout Istanbul, with roughly half that number drafted into the centre to cordon off all the avenues, streets and alleys around the square.
The TURK-IS labour confederation was however allowed access to the square to lay wreaths in memory of 34 people killed during a 1977 May Day protest, when unknown demonstrators fired shots into the air, sparking panic.
The union organised another May Day rally in Istanbul, in Kadikoy Square on the Asian side of the city.
Public transport was paralysed in the sprawling city of more than 13 million as the authorities blocked roads, cancelled ferry services and closed metro stations in a bid to cope with two crowds of demonstrators on either side of the Bosphorus.
Erdogan warned protesters last week to "give up hopes" of meeting on Taksim, but activists and leftist unions had long vowed to ignore the ban.
And Istanbul Governor Huseyin Avni Mutlu said Wednesday that the ban was based on intelligence reports indicating "illegal terrorist groups" were planning unrest at Taksim.
Violent protests between police and protesters on May Day last year, triggered after a similar ban, were followed weeks later by protests that snowballed into one of the biggest challenges to Erdogan's 11-year rule.