Riot police in Istanbul used water cannon and tear gas Thursday against a crowd of thousands who tried to defy a May Day ban on demonstrations, leaving some 70 protesters and 19 police injured, Agence France-Presse reported.
Hundreds of riot police moved on protesters seeking to breach the barricades leading to Taksim Square, declared off limits to Labour Day demonstrators as the epicentre of anti-government protests in recent months.
Smoke rose above the Besiktas district, home to Prime Minister Recep Tayyip Erdogan's office, following the police charge.
The Istanbul governor's office said in a statement that 90 people, including 19 police officers were hurt and 142 were arrested across the city as police clashed with flag-waving and balaclava-wearing protesters hurling stones and Molotov cocktails.
In the capital Ankara, police fired volleys of tear gas and jets of water on hundreds of protesters trying to march to the Kizilay Square, also declared off limits.
In Istanbul's Besiktas, Mahmut Tanal, a lawmaker from the main opposition Republican People's Party was beaten by police who tried to pushed him away from a water cannon truck.
"This is a picture that you can only see in countries which are governed by dictator regimes," Tanal told AFP, vowing to sue both Erdogan and the interior minister over the incident.
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 in to cordon off Taksim square.
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.
By evening tension had abated and the protesters slowly dispersed.
Rights group Amnesty International slammed the police crackdown on May Day protesters as "the Turkish authorities' stock response to peaceful protests".
"The use of tear gas and water cannon against peaceful protesters today by police in Istanbul is a reprehensible move to crack down on free expression and peaceful assembly," it said in a statement.
Worker unions, whose members were out on the street in defiance of the government ban, denounced the police response in a joint statement and said the barricades have turned Istanbul into a "giant prison".
"The government, which has adopted oppression, injustice and lawlessness as principles, has seen that it is not capable of creating an empire of fear," the statement said.
Erdogan warned protesters last week to "give up hopes" of meeting on Taksim and suggested a rally area in the Yenikapi district on the outskirts of Istanbul, but only six people turned out at the venue despite free transport.
Istanbul Governor Huseyin Avni Mutlu said Wednesday the ban was based on intelligence reports indicating "illegal terrorist groups" were planning unrest at Taksim.
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 gunmen fired on a peaceful crowd.
Another May Day rally in Istanbul, in Kadikoy Square on the Asian side of the city, was celebrated without incident.
Taksim Square was only opened to May Day rallies in 2009, ending a three-decade ban brought on by the 1977 tragedy.
Parliament reinstated May Day as a national holiday in 2009 and decided to fully open the square to celebrations, only to ban it again last year citing renovation work.
Violent protests between police and May Day protesters last year were followed weeks later by a wave of nationwide protests that snowballed into one of the biggest challenges to Erdogan's 11-year rule.
Eight people died and 8,000 were injured when police cracked down heavily on a peaceful campaign to save Istanbul's Gezi Park - adjacent to Taksim - from redevelopment, earning Turkey a harsh rebuke from its Western allies.
Sporadic protests have continued against controversial measures taken by Erdogan in response to a massive corruption scandal implicating key government allies, including an Internet crackdown that saw Twitter banned for two weeks.
Despite the protests, the corruption scandal and Erdogan's perceived authoritarianism, the premier's AKP party scored a resounding victory in March 30 local elections, winning 45 percent of the vote.