Protests in Paris over a controversial French labor law turned violent once again as French riot police fired teargas and stun grenades Thursday in clashes with angry opponents. Violent protests have become a common thing for the country as France has been rocked by anti-labor reform protests for the last seven months.

Four demonstrators and 15 police were hurt including two officers who sustained burns due to Molotov cocktails as tens of thousands rallied against the law forced through by the Socialist government. Police used water cannon and tear gas as protests also turned violent in Nantes in western France, one of at least 10 provincial cities that saw rallies. "The violence is unacceptable," said Interior Minister Bernard Cazeneuve, noting that police had arrested 62 people across the country, 32 of whom were kept in custody. Authorities said some 78,000 people rallied overall nationwide, including 13,000 in Paris. Organizers put numbers across France at around 170,000, saying 40,000 protested in Paris.

Unions in France vowed to keep fighting the country's new labor law, but admitted on Thursday that months of street protests were now coming to an end. The rallies, which kicked off in March under the slogans LoiTravail (Labor Law) and NuitDebout (Rise Up At Night), have repeatedly turned violent, frequently ending in arrests and injuries.

The violence unleashed by the reforms peaked on June 14, just four days after the start of the Euro 2016 football championships in France, when around 40 people were hurt and dozens arrested. CGT leader Philippe Martinez has appealed to workers to continue "fighting tooth and nail to stop it (the law) crossing the threshold" of their companies. French President François Hollande, who has yet to announce whether he will seek re-election next year, had hoped for a signature reform to boost his dire approval ratings. Currently, around four out of five French voters oppose him standing for a second term.

As well as the protests, scores of flights in and out of the country were also cancelled as air traffic controllers went on strike to protest the law. "We will show them that, law or no law, we will always stand against them," Francois Roche, a member of the hardline CGT union demonstrating in Marseille, told AFP. Turnout nationwide was far lower than at the first rallies earlier this year which saw hundreds of thousands of people take to the streets. One of the focal points Thursday was the eastern city of Belfort, where the government is locked in a battle with train-building giant Alstom over the future of a locomotive factory threatened with closure. Hundreds of demonstrators marched through the city, chanting "Alstom is Belfort, Belfort is Alstom."

Belfort's history is intertwined with that of Alstom, which produced its first steam train there in 1880. The plant now assembles high-speed TGV train locomotives. Last week, Alstom had announced it would close the plant due to a lack of orders and move production to a site 200 kilometers to the north.

The prospect of up to 400 job losses is deeply embarrassing for the Socialist government eight months ahead of presidential and parliamentary elections, in which high unemployment is expected to be a key issue.

The law is aimed at loosening France's notoriously rigid employment laws. According to the new labor law, the 35-hour week remains in place, but as an average. Firms can negotiate with local trade unions on more or fewer hours from week to week, up to a maximum of 46 hours. Firms are given greater freedom to reduce pay.