SOME 109 people were in custody in Paris overnight suspected of offences including carrying prohibited weapons and firing projectiles after May Day protests against reforms by French President Emmanuel Macron turned violent, French authorities said.

Interior Minister Gerard Collomb visited the site of Tuesday’s heated demonstrations in the city’s Left Bank less than 24 hours after six cars were burned, a McDonald’s restaurant was smashed up and car shops were vandalised.

“We’re searching for the ringleaders,” Mr Collomb said, adding that such acts “will not go unpunished.”

Authorities blamed the violence on masked attackers from a libertarian group called the Black Blocs that numbered around 1200 people in total and were on the margins of the 20,000-strong protest.

The television images have shocked the country and turned criticism toward the Paris authorities, whom some accuse of being slow to react to quell the tensions.

Mr Collomb defended his police to the Associated Press, saying that the masked individuals’ infiltration among normal protesters meant that the ability of the authorities to stop the violence without threatening the safety of the public was hampered. “We couldn’t intervene while there were people in front of the Black Bloc activists, to avoid having people ending up wounded or dead. That’s the danger,” he said.

Though several people were injured — including a police service worker — and even hospitalised, Mr Collomb said on France 2 Television he was pleased “no one was seriously injured”.

French authorities could not confirm a Wednesday report by Iranian state television IRIB that one of its cameramen suffered a head injury. Paris Police Prefect Michel Delpuech said “the desire of the radical activists was to spiral the day out of control”.

Opposition figures seized upon the absence of Mr Macron, who was on a visit to Australia, to paint an image of disorder in a country without a leader amid criticism that police did not act quickly enough to cope with the violence.

Mr Macron responded from Sydney: “There is a government. There is a state that’s being run and it will continue to react.”

Workers, students and others marched through cities around France during the May Day protests, aimed at expressing discontent over Macron’s plans to overhaul some employee protections.