More than 600,000 protesters have taken part in rallies and marches across France, according to France's interior ministry, with five unions joining a day of action demanding more money for wages and public services.
The left-wing CGT union put the number of people taking part in Thursday's mobilisation at 1.57 million and hailed the figure as "a level unmatched" since 2023, citing big protests in Paris, Marseille, Bordeaux and Lille.
As darkness fell in Paris, Prime Minister Sébastien Lecornu said he would convene a "social conference" with unions and employers next Monday.
The wave of protests began in September over poor conditions and resources at lycées (high schools), before spreading to universities, workers and a revived "yellow-vest" movement against high prices.
The unions had vowed to take the co-ordinated move against the government "to the next level", and CGT chief Sophie Binet had said their message was that "the only thing that will bring this mobilisation to a halt is responding to our demands".
Interior Minister Laurent Nuñez had earlier deployed 70,000 police, vowing "an extremely firm response" to any potential outbreaks of violence.
Some unrest was reported in several cities.
A car was set alight near the Gallieni bridge over the Rhône river in Lyon, as hundreds of activists from the radical left-wing "black bloc" clashed with police.
Clashes were also reported in the north-western city of Rennes, where the local prefect said a "hostile group of masked individuals" had gathered in front of the main union march. Tear gas was used to clear a square in the south-western city of Bordeaux and a teenager was hurt in a stabbing involving a student at a high-school blockade in the Seine-Saint-Denis suburb of northern Paris.
But the trouble was not on the scale seen during the last big day of protests, on Saturday 17 October, when more than 2,000 stores were looted and historic buildings set on fire.
The provisional numbers reported on Thursday were higher than on 17 October, considered the biggest day of rallies until now when the interior ministry said 550,000 people had turned out and the unions counted 800,000.
Earlier on Thursday the leader of the CFDT union, Marylise Léon, said she would be happy if the protests matched that earlier level.
A coalition of unions across the public and private sector had urged workers, pensioners and young people to join Thursday's day of strikes to intensify pressure on the government. In particular they are seeking a rise in the minimum wage, or Smic, which is currently €12.31 (£10) an hour.
Sophie Binet told reporters at the start of a march in central Paris that protesters had "just reached a new level in their mobilisation" and were demanding immediate answers.
An estimated 9.89% of civil servants were taking part in the strikes, according to government figures.
Disruption was reported in schools, hospitals and public transport, and the Eiffel Tower and some exhibition rooms at the Louvre museum in Paris had to close.
Workers were also asked to halt production at oil refineries and France was expected to import more electricity than it produced on Thursday because of disruption at nuclear plants.
