A nationwide strike has severely disrupted schools and public transport across France.
Workers are angry at being forced to retire later or face reduced pensions.
School and transport workers have been joined by police, lawyers, and hospital and airport staff for a general walkout that could include millions of people.
France’s largest nationwide strike in years was agreed by unions unhappy with President Emmanuel Macron’s plans for a universal points-based pension system.
“What we’ve got to do is shut the economy down,” said union official Christian Grolier of the Force Ouvrière (Workers’ Force). “People are spoiling for a fight.”
Interior Minister Christophe Castaner said on the eve of the strike he expected almost 250 demonstrations nationwide, some of which he said could turn violent.
“We know there will be lots of people in these protests and we know the risks. I have requested that systematically when there is rioting or violence we make arrests immediately,” he said.
On Paris’s famous Champs-Élysées boulevard, riot police began searching pedestrians’ bags before dawn, and shops on a planned protest route have been ordered to close.
Transport networks ground to a near-halt in some areas on Thursday morning.
Some 90% of high-speed TGV and intercity trains have been cancelled, with buses also affected. In Paris, just five of the city’s 16 metro lines are running.
The early rush hour saw deserted stations as commuters shared car rides, took to their bikes or worked from home.
Some of those hit by bus and train strikes took to their bikes in Paris
“Public transport will be very difficult today, as it will tomorrow and probably this weekend too,” junior transport minister Jean-Baptiste Djebbari told French station RTL radio.
Train operators Eurostar and Thalys, which run international services, have cancelled at least half their services linking Paris with London and Brussels. Eurostar will operate a reduced timetable until 10 December.
Air travel has been badly affected, with hundreds of flights cancelled. Air France said it would cancel 30% of internal flights and 30% of short-haul international flights, amid walk-outs by air traffic controllers.
People in Nice prepare for industrial action with posters that read: “Everyone on strike on 5 December”
Low-cost carrier EasyJet has cancelled 223 domestic and short-haul international flights, and warned passengers to expect delays.
Nurses and hospital staff, lawyers and police officers, refuse collectors, energy staff and postal workers are among others participating in industrial action.
France’s health minister said it was not yet clear how badly hospitals would be affected, but preparations had been made to deal with the strike.