Twenty-six people were hurt and authorities made 15 arrests today as protests in Paris over disputed labour reforms descended into violent clashes between riot police and masked troublemakers.
Police fired water cannon in southern Paris to quell rioters as "several hundred" masked protesters lobbed objects at police in bloody scenes in the French capital.
The clashes erupted as the international spotlight was on France as the host of the Euro 2016 football championships, which have also been marred by violence between fans.
Strikes closed the Eiffel Tower and disrupted transport links as tens of thousands of fans pour into the country for Europe's showcase football event.
During the Paris unrest, several demonstrators stormed a building site and hurled wooden palettes at riot police.
Pictures showed one man being led away by officers in riot gear with blood streaming from a wound above his eye, his white T-shirt splattered with blood.
The strike is the latest in months of industrial action that has seen air and rail transport severely disrupted, fuel shortages and rubbish piled up on the streets of Paris.
"I've been to all the demos since March because I want to live in dignity, not just survive," said Aurelien Boukelmoune, a 26-year-old technician marching in Paris.
"I want the reforms to be withdrawn, pure and simple. Only then will it stop. For the government's sake, they should withdraw the law, otherwise we'll block the economy."
With France on high alert over fears of attacks during Euro 2016, overstretched security forces had feared the demonstrations could turn violent and banned 130 known troublemakers from taking part.
The terrorism threat was thrust back into the spotlight after a man claiming allegiance to Islamic State jihadists killed a policeman and his partner at their home in a northwestern Paris suburb late yesterday.
The latest in a wave of protests that began in March coincides with a French Senate debate on the reforms, which are aimed at making the job market more flexible and reducing high unemployment but which critics see as too pro-business.
President Francois Hollande's Socialist government has voiced hope the latest day of protest will be a last stand for the movement.
But Philippe Martinez, head of the far-left CGT union that spearheaded last month's blockades of fuel depots and an ongoing rail strike, predicted a "very strong mobilisation".
The CGT laid on more than 600 buses to transport demonstrators to Paris and said it hoped to attract more support than in March, when it claimed 1.2 million people took to the streets. Authorities put the March figure at 390,000.
Paris police chief Michel Cadot said he expected "maybe more than 50,000 demonstrators" in Paris alone on Tuesday.
Two further protest days are set for later this month.
