France's largest nationwide strike in years has severely disrupted schools and transport.
Workers are angry about planned pension reforms that would see them retiring later or facing reduced payouts.
More than 800,000 workers from a wide range of professions demonstrated against the changes. Some cities saw clashes between protesters and police.
President Emmanuel Macron wants to introduce a universal points-based pension system.
That would replace France's current system, which has 42 different pension schemes across its private and public sectors, with variations in retirement age and benefits.
"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."
Since coming to power, Mr Macron has pushed through other reforms including relaxing labour laws and cutting taxes for businesses.
What's the latest?
More than 800,000 people had joined demonstrations in more than 100 cities across France, the interior ministry said. The CGT union said 1.5m people had turned out, including 250,000 in Paris.
The CGT also said workers had blocked seven of the country's eight oil refineries, potentially causing fuel shortages if the strike continues.
In Paris, popular tourist sites including the Eiffel Tower, the Musée d'Orsay and the Palace of Versailles were shut for the day.
🇫🇷 En raison du mouvement de grève national, je suis fermée aujourd'hui. Mon parvis reste néanmoins accessible gratuitement.— La tour Eiffel (@LaTourEiffel) December 5, 2019
🇬🇧 Due to a national strike, I'm closed today. Access to my esplanade remains open and free of charge.#tourEiffel #Eiffeltower pic.twitter.com/882RfZ3xct
At some of the marches there were clashes between protesters and police.
Police in Paris had arrested 71 people, officials said. There were numerous reports of vandalism in the city. Violence was also reported in Nantes, Bordeaux and Rennes.
How has transport been affected?
- Some 90% of high-speed TGV and inter-city trains were cancelled
- In Paris, just five of the city's 16 metro lines were running
- Train operators Eurostar and Thalys cancelled at least half their services linking Paris with London and Brussels. Eurostar will operate a reduced timetable until 10 December
- Hundreds of flights were cancelled
- Air France cancelled 30% of internal flights and 10% of short-haul international flights amid walkouts by air traffic controllers
- Low-cost carrier EasyJet cancelled 223 domestic and short-haul international flights, and warned passengers to expect delays.
Meanwhile the Extinction Rebellion group said it had sabotaged thousands of e-scooters by painting over the QR codes that smartphone users scan to unlock the vehicles.
Ce matin (et en soutien à la #grevedu5decembre) des rebelles de #ExtinctionRebellion Paris, Lyon et Bordeaux ont mis HS 3600 trottinettes 🛴!— Extinction Rebellion France 🐝🌺 (@xrFrance) December 5, 2019
En raison de leur prod. très énergivore, de leur faible durée de vie, ces véhicules ne représentent qu'un instrument de + de #greenwashing pic.twitter.com/WFgna1Zugw
The group said this was because e-scooters - despite being widely viewed as an ecologically-friendly form of transport - actually required large quantities of energy and resources during their manufacture and had short life cycles.
How do French workers view the reforms?
Teachers and transport workers were joined by police, lawyers, hospital and airport staff, and other professions for the general walkout.
Train driver Cyril Romero from Toulouse told France Info he would reconsider his job if the reforms went through.
"I started in 2001 with a contract that allowed me to leave at 50. But like everyone else, I got the reforms which pushed back my early retirement age to 52-and-a-half and then, in reality, 57-and-a-half for full pension. Now they want to make us work even longer."
An unnamed history teacher, writing in HuffPost, was planning to strike on Friday as well as Thursday.
"For me, the pension reforms are one punch too many. We're fighting not to lose hundreds of euros of pension a month - after more than 40 years in a job.
"How can you even think of ending your career in front of pupils beyond the age of 70, in worsening conditions and on what for many of us is just a minimum wage?"
How much support is there for the strike?
Some trade union leaders have vowed to strike until Mr Macron abandons his campaign promise to overhaul the retirement system.
One opinion poll put public support for the strikes at 69%, with backing strongest among 18- to 34 year olds.
However farmers, whose pensions are among the lowest in the country, are not taking part.
The Macron administration will hope to avoid a repeat of the country's general strike over pension reforms in 1995, which crippled the transport system for three weeks and drew massive popular support, forcing a government climbdown.
A number of "gilets jaunes" (yellow-vest) protesters had said they planned to join the demonstrations.
The movement, which emerged at the end of 2018, started with demonstrations against a sharp increase in diesel taxes, but has broadened to reflect anger over higher living costs and President Macron's economic policies.
Are Macron's reforms really that controversial?
Mr Macron's unified system - which he says would be fairer - would reward employees for each day worked, awarding points that would later be transferred into future pension benefits.
The official retirement age has been raised in the last decade from 60 to 62, but remains one of the lowest among the OECD group of rich nations - in the UK, for example, the retirement age for state pensions is 66 and is due to rise to at least 67.
The move would remove the most advantageous pensions for a number of jobs ranging from sailors to lawyers and even opera workers.
Meanwhile, those retiring before 64 would receive a lower pension. For example, someone retiring at 63 would receive 5% less, so unions fear it will mean having to work longer for a lower pension.
A recent poll concluded that 75% of people thought that pension reforms were necessary, but only a third believed the government could deliver them.