Paris - French and Turkish police fired tear gas at protesters as tensions erupted in both countries during May Day rallies Sunday, while thousands marched across the globe for the annual celebration of worker's rights.
From Moscow to Madrid, workers chanted demands for higher wages, better conditions and more job security as many countries battle economic uncertainty and high unemployment.
Thick clouds of tear gas hung above the Place de la Nation square in Paris where youths in balaclavas and ski masks lobbed cobblestones and bottles at black-clad riot troops shouting: "Everyone hates the police."
Police estimated some 17,000 protesters marched throughout the French capital for a rally riding a wave of anger against planned labour reforms set to come before parliament on Tuesday.
Ten people were arrested, while one demonstrator and one officer were lightly injured in the scuffles, police said.
The May Day rally was the second protest against the reforms in a week to descend into violence led by troublemakers known as "casseurs" (breakers) who actively seek confrontation with security forces.
"We will respond with the greatest of determination to these troublemakers... the attacks and violence against security forces are unacceptable," said French Prime Minister Manuel Valls on Sunday.
While the government hopes the reforms will reduce chronic unemployment of about 10 per cent, critics believe they threaten hard-won workers' rights by making it easier to lay off people in lean times.
The government has already watered down the bill but this has failed to calm the anger among students and workers.
"Withdraw, withdraw the labour law. Not amendable, not negotiable," protesters chanted.
In Istanbul, police clamped down on unauthorised protests at a time of particular tension after a succession of deadly attacks this year in Turkey blamed on jihadists and Kurdish militants.
Around 25,000 police were on duty, cordoning off the central Taksim Square and releasing volleys of teargas and water cannon on those trying to make their way to the protest hotspot, an AFP photographer said.
In the flashpoint area of Okmeydani, masked radical leftists threw Molotov cocktails and firecrackers at police and created burning barricades out of junk.
The office of the Istanbul governor said that 207 people were detained around the city for trying to march on Taksim. It said that 40 Molotov cocktails, 17 hand grenades and dozens of fireworks were seized.
In a separate incident, a man in his 50s was killed when he was run over by a police water cannon vehicle.
Hundreds of labour and union activists took part in an officially-sanctioned rally elsewhere in the city.
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.
International Workers' Day was started in Chicago in 1886 by a union demanding an eight-hour work day and is now celebrated around the world.
In Moscow around 100,000 workers joined a May Day parade on the city's Red Square, waving Russian flags and balloons near the Kremlin walls, police said.
The carefully choreographed parade took place amid an economic crisis brought on by Western sanctions over Ukraine and low oil prices.
Hundreds of thousands marched in Cuba at a rally condemning a campaign to "destabilise" leftist governments around Latin America.
"This May 1 is also a day to condemn the manoeuvres aimed at... reversing the gains achieved in social policy in our America and destabilising the leftist and progressive governments in power," Ulises Guilarte, the secretary general of the Workers' Central Union of Cuba, told a massive crowd on Havana's Revolution Square.
Thousands marched in Madrid with banners proclaiming: "Against budget cuts and for retirees." In Austria, embattled Chancellor Werner Faymann faced jeering and boos as he addressed around 80,000 people in Vienna, a week after the government's disastrous defeat at the hands of the far-right in a presidential ballot.
In South Korea, planned labour reforms have also sparked anger among workers, and tens of thousands protested against the bill.
Labour activists say the reforms being pushed by President Park Geun-Hye and her conservative Saenuri Party will make it easier for companies to sack workers.
"Let's fight together against the evil bill!" activists and union members chanted during a protest in Seoul.