French police fired tear gas, stun grenades and water cannon in battles with "yellow vest" protesters trying to breach security cordons on the Champs Elysees in Paris on Saturday ahead of a third rally against high living costs.
Police said 81 people had been arrested amid concerns that violent far-right and far-left groups were infiltrating the "yellow vests" movement, a spontaneous grassroots rebellion over the struggle of many in France to make ends meet.
For more than two weeks, the "gilets jaunes" (yellow vests) have blocked roads in protests across France, posing one of the largest and most sustained challenges Emmanuel Macron has faced in his 18-month-old presidency.
In Paris, masked and hooded protesters picked up and hurled crowd barriers and other projectiles in running battles with police around the world famous Champs Elysees boulevard.
Three policemen and seven protesters had been injured, spokeswoman Johanna Primevert said.
"The thugs are a minority and have no place in these demonstrations," government spokesman Benjamin Griveaux told LCI television.
Prime Minister Edouard Philippe cancelled a planned speech at a rally for Macron's party to monitor developments in Paris.
Several hundred yellow vests sat down under the Arc de Triomphe at the top of the avenue, singing La Marseillaise, France's national anthem, and chanting, "Macron Resign!"
On the facade of the towering 19th-century arch, protesters scrawled in big black letters: "The yellow vests will triumph."
After several hours of skirmishes in the morning, security forces appeared to clear the area around the Arc where rioters and peaceful protesters had mingled, pushing them into adjacent streets.
Along the Champs Elysees, peaceful demonstrators held up a slogan reading, "Macron, stop treating us like idiots!"
Macron won't be bounced by "thugs"
Macron said on Tuesday he understood the anger felt by voters outside France's big cities over the squeeze that fuel prices have put on households, but insisted he would not be bounced into changing policy by "thugs".
Police unions said across France there were some 31,000 protesters and 582 road blockages.
A week ago thousands of protesters, who have no leader and have largely organised themselves online, converged on Paris for the first time, turning the Champs Elysees into a battle zone as they clashed with police firing tear gas and water cannon.
"What message do the yellow vests want to pass today? That we set France on fire, or find solutions? I find this (violence) absurd," Jacline Mouraud, a prominent activist within the yellow vests movement, told BFM television.
But a retired yellow-vest protester said: "The government is not listening. Revolution cannot happen without violence."
The outburst of anger is strongest on the outskirts of smaller provincial towns and villages, and underlines the gap between metropolitan elites and working class voters that has boosted anti-establishment politics across the Western world.
The immediate trigger for the protest wave was Macron's decision to raise tax on diesel fuel in a move to encourage the driving of less-polluting cars.
The yellow vests take their name from the high-visibility jackets all motorists in France must carry in their vehicles.
Ahead of Saturday's protests, workmen erected metal barriers and plywood boards on the glass-fronted facades of restaurants and boutiques lining the Champs Elysees, which was closed to traffic with pedestrians funnelled through checkpoints.
For now, the "yellow vests" enjoy widespread public support.
When they began, the protests caught Macron off-guard just as he was trying to counter a fall in his popularity rating to 30 percent. His unyielding response has exposed him to charges of being out of touch with ordinary people.