Rioting broke out across French cities on Wednesday as protesters linked to a decentralised "Block Everything" campaign clashed with police, leaving more than 350 people arrested and prompting authorities to deploy tens of thousands of security forces.

Demonstrators erected barricades, attempted to block roads and train stations, and staged go-slow operations that paralysed traffic in parts of the country. Activists shut stretches of the Paris ring road and placed barriers in front of secondary schools and bus stations. In Lyon, officers used tear gas against about 100 people who tried to halt rail traffic at Perrache station. The A10 motorway was blocked near Poitiers, and barricades were reported outside Paul Sabatier University in Montpellier. Protesters also targeted fuel depots, and some online messages urged participants to fill shopping bags in supermarkets and leave without paying.

The movement, which lacks central leadership and is said to be organised largely via social media, drew support from the CGT, France's largest trade union. Sud-Raid, a rail workers' union, posted on X that "the fall of the government is good, but it's insufficient," and encouraged strikes. Authorities said some 80,000 police and gendarmes were deployed around the country to respond to the unrest.

Interior Minister Bruno Retailleau described the situation as having an "insurrectional mood," saying the movement had been "hijacked by the ultra-Left" and that some participants were determined to carry out violent actions. Clashes were reported in several cities, with riot police using water cannon and making arrests as they cleared blockades.

The protests came less than 24 hours after President Emmanuel Macron appointed Sébastien Lecornu as prime minister, the seventh to serve under Macron in under nine years. Lecornu has said he will attempt to build a parliamentary majority to pass an austerity budget backed by Macron. His predecessor, François Bayrou, was forced out after losing a confidence vote in the National Assembly. Bayrou had proposed deep public spending cuts, including measures described by his office as targeting some £35 billion in savings, steps to cut two public holidays and a freeze on some pensions and welfare payments.

Critics and many protesters say the planned austerity measures will exacerbate economic hardship and have expressed anger at the government's direction. "Everyone is sick of Macron, and his government," said a 19-year-old student, Nicolas, at a Paris protest, adding that he expected the new prime minister to be "as useless as the last one."

Observers note similarities between the current campaign and the Yellow Vest movement that erupted in 2018, in both its decentralised organisation and its capacity to paralyse transport and commerce. The Yellow Vests staged repeated weekend demonstrations that eventually prompted policy changes by Macron but also caused widespread damage.

Union-led calls for further action include planned stoppages and strikes on Sept. 18, when air traffic controllers and other sectors are expected to join protests. French authorities said they would maintain a substantial security presence to prevent further escalation and to protect critical infrastructure as demonstrations continue.