Tens of thousands of people were set to protest across France on Saturday in a new show of anger against the government with Paris police imposing strict security to prevent an unauthorized gathering close to the Elysee Palace.

The protests mark the fourth weekend in a row of demonstrations, which have burst on the scene as the country tilts towards presidential elections in five months' time in which the far right sees its best chance yet to win power.

Authorities expected up to 170,000 people to protest nationwide, including 60,000 in Paris. The demonstrations come two days after mass protests by unions on November 5 accompanied by strikes.

Some 70,000 members of the security forces were deployed Saturday, ready to move in quickly after mass protests on October 17 degenerated into the worst riots seen in France in years.

Unions planned to stage a march along a traditional route, from the Place de la Republique in central Paris to Place de la Nation in the east of the city.

But the Yellow Vests movement -- a group whose protests shook President Emmanuel Macron in the early years of his rule almost a decade ago -- has called for a rival demonstration at the Place de la Concorde in central Paris, a stone's throw from the Elysee Palace where the president resides and from the lower house of parliament.

This action has been banned by the authorities, and on Saturday morning a large police presence was visible in the vicinity to prevent protesters getting close.

Paris police said they had carried out more than 840 checks on individuals at train stations in Paris and its inner suburbs by late morning.

Protest marches were already underway in cities from Marseille in the south, Bordeaux in the southwest and Lille in the north, AFP reporters said. Meanwhile shop windows of stores in Paris and other cities were again barricaded with wooden shutters to prevent ransacking.

"The risk is exactly the same as on previous Saturdays," said Interior Minister Laurent Nunez, calling on authorities "not to lower their guard in the face of more fragmented -- or even sporadic -- incidents, where the level of violence will not diminish in intensity".

"If there are any rioters or looters... we'll be ready and waiting for them," he said.

The Yellow Vests movement called for its banned rally to go ahead in a show of defiance to what it viewed as an attempt to suppress the French right to protest.

"We are calling for mass disobedience," said Benjamin Ball, a member of its coordinating committee.

The wave of demonstrations was sparked by a movement in late September by high school students angered by conditions at their establishments. These teens, joined by university students, remain at the heart of the protests.

The police response has faced criticism for being heavy-handed, with dozens of internal investigations launched into allegations of brutality against demonstrators.

After several instances of apparent police brutality against AFP reporters covering the protests, the international news agency on Friday urged protection for its journalists.

The government is grappling with ways to find solutions but is constrained by France's gigantic debt pile which is already spooking markets.

Prime Minister Sebastien Lecornu was to hold a meeting with unions and employer federation representatives on Monday to discuss wages and purchasing power.

"The only thing that will bring the protests to an end is a response to the demands that have been put forward for several weeks by workers, civil servants, young people and pensioners," an inter-union coalition said on Friday.

Student and teacher groups in France have called for a new strike on Tuesday to keep pressure on the government for more education spending, saying they were "in a position of strength (and) the government in a position of weakness and starting to yield".

Polls meanwhile show that far-right candidate Marine Le Pen is the favourite to win the Elysee in 2027 with her main rival currently not one of Macron's centrist former allies but hard-left leader Jean-Luc Melenchon. Melenchon was due to address a rally later Saturday.

@AFP