French police clashed with hundreds of demonstrators in Paris and other cities during union-led protests against President Emmanuel Macron's increase in the retirement age, as workers staged Labour Day rallies across Europe.
Protestors pelted Paris police with Molotov cocktails and fireworks, torched building materials and smashed up bus stops. Demonstrators marching peacefully booed the police as they responded with tear gas and baton charges.
Emergency services used water canon to put out a fire which blackened the windows of nearby flats. One officer was badly injured when he was struck by a fiery projectile.
Violence also erupted in Lyon and Nantes, where some vehicles were set ablaze and business premises were trashed. Around 300 people were arrested on a day some 782,000 people took to the streets, according to the interior ministry.
Macron last month raised the retirement age by two years to 64 despite multi-sector strikes, in a move that drove his popularity down to near the record lows seen during the "Yellow Vest" crisis of 2018-2019.
The reform has crystallised discontent against a president perceived by many as aloof and indifferent to their daily hardships, and he has been met during walkabouts aimed at rebuilding support by heckling and pot banging.
Trade unions had called for a big turnout as they seek to force a U-turn by Macron's government, which forced its pension law through without a final vote in the National Assembly, where it lacks a working majority.
Opinion polls show a substantial majority of French people oppose the higher retirement age.
The pension system is a cornerstone of France's cherished social protection model. A banner reading "Retirement before arthritis!" summed up the disgust felt by many at being told to work longer.
Macron says the French reform is needed to help shore up one of the industrialised world's most generous pension systems.
French pension payments as a share of pre-retirement earnings are comfortably higher than elsewhere and a French man typically spends longer in retirement than those in other OECD nations.