Strike action over changes to the French labour law have disrupted many cities across the country.
Tens of thousands gathered in Paris for the eighth time in two months.
“Divisions are emerging inside the government as Euro 2016 approaches,” said Olivier Besancenot, former head of the far-left New Anti-Capitalist Party. “You can’t have two and a half months of mobilization – this is the eighth strike, strikes are continuing in key sectors – imagine the tournament being held without fuel, without cars, without transportation or even without lights.”
Protesters met with waves of tear gas as police fought bands of violent masked marchers in the French capital.
Police arrested 77 people as tens of thousands made their way from the Bastille plaza through eastern Paris.
Volley after volley of tear gas filled the air, as authorities struggled to quell public anger at a government attempt to change the way France views work.
The reforms are aimed at creating jobs, but opponents say they would worsen working conditions, make it easier for companies to fire workers and increase unemployment.