France is seeing renewed anti-government protests, with nearly 90,000 security personnel on the streets.
Some 8,000 officers and 12 armoured vehicles have been deployed in Paris alone, where about 5,000 people have gathered in the city centre.
At least 127 people have been held in Paris. Video footage showed several episodes of police firing tear gas.
The "yellow vest" movement opposed fuel tax rises but ministers say it's been hijacked by "ultra-violent" protesters.
Last week, hundreds of people were arrested and scores injured in violence in Paris - some of the worst street clashes in the French capital for decades.
What is happening this weekend?
About 5,000 people gathered on the Champs-Elysées and marched a short distance to a police cordon where they stopped.
There have been a few confrontations, with police firing tear gas at protesters in a side street as tensions flared.
The gas is believed to be phosgene, much stronger than substances used previously.
Le Monde journalist Aline Leclerc tweeted (in French) that there were fewer protesters, and that police were searching bags and confiscating items such as helmets and spectacles.
She said that the demonstrators were mostly men aged between 20 and 40, with women and older men apparently put off by the threat of violence.
The BBC's Hugh Schofield, on the Champs-Elysées, says he was told by protesters that their masks, used to protect against tear gas, had also been removed by police.
Police say at least 127 people have been detained at railway stations and in the streets, with more than 350 stopped for identity checks.
About 65,000 security officers were deployed across the country last weekend, but that has been increased to 89,000, even though Interior Minister Christophe Castaner said he expected fewer protesters than last weekend, perhaps about 10,000 nationwide.
"Ten thousand is not the people - it's not France," he said.
Some calls on social media for attacks on police and the Élysée palace in an "Act IV" drama have been unnerving.
One MP, Benoît Potterie, received a bullet in the post, accompanied by the words: "Next time it will be between your eyes."
Six matches in the top tier of France's football league have been postponed. The Louvre, Musée d'Orsay and other sites are closed in Paris.
Mayor Anne Hidalgo issued a plea: "Take care of Paris on Saturday because Paris belongs to all the French people."
Where are we with the yellow vest movement?
The "gilets jaunes" protesters are so-called because they have taken to the streets wearing the high-visibility yellow clothing that is required to be carried in every vehicle by French law.
The BBC's Lucy Williamson in Paris says that over the past few weeks, the social media movement has morphed from a protest over fuel prices to a leaderless spectrum of interest groups and differing demands.
Who are the 'gilets jaunes'?
Ball in Macron's court after violent protests
Its core aim, to highlight the economic frustration and political distrust of poorer working families, still has widespread support, our correspondent says.