Turkish police have briefly clashed with protesters in Istanbul after putting the city under a security lockdown in a bid to thwart demonstrations on a tense Labour Day.
Al Jazeera's Can Hasasu, reporting from the central Besiktas district, said about 2,000 people from leftist groups had earlier gathered there before Friday's clashes.
Police used tear gas and water cannon to disperse the crowd. Protesters retaliated by throwing stones and hurling firecrackers at officers.
"The police claim they used these measures against a small group of masked men, but they later used it on the rest of the group which was peacefully demonstrating," Hasasu said, adding that the Besiktas square was cleared after the incident.
Clashes were also reported in the city's Okmeydani district. The area has been a protest hotspot since anti-government clashes rocked Istanbul in 2013.
Police tightened security across the city, blocking all vehicle access to the central Taksim Square, and halting accessibility by public transport.
Shortly afterwards, the clean-up of the streets started and the traffic movement was restored.
At least 10,000 police were mobilised as a preventative measure.
The governor of Istanbul, Vasip Sahin, said demonstrations would not be allowed in Taksim Square as the area was "not adapted to the commemorations for May 1" and there was a risk to "security and property".
Security checkpoints restricting access to residents only and preventing groups from entering were set up in the Taksim area.
Unions and activists have made clear they still intend to take to the streets, in defiance of the restrictions.
Labour Day has seen recurring clashes in previous years between security forces and leftist protesters.
This year's demonstrations come just two months after parliament passed a controversial security bill giving the police greater powers to crack down on protests.
Source: Al Jazeera and agencies