"Yellow vest" protesters clashed with police in several French cities, smashing their way into a government ministry in Paris with a forklift.

Benjamin Griveaux - a government spokesman evacuated from his ministry in central Paris on Saturday when a handful of protesters in high-visibility vests smashed down the large wooden door to the ministry compound - denounced the break-in as an "unacceptable attack on the Republic".

"Some yellow vest protesters and other people dressed in black ... got hold of a construction vehicle which was in the street nearby and smashed open the entrance gate to the ministry," he told the AFP news agency.

They briefly entered the courtyard where they smashed up two cars, broke some windows and then escaped, Griveaux added, saying police were trying to identify them from security footage.

The Interior Ministry put the number of protesters who took to the streets across France at 50,000, compared with 32,000 on December 29 when the movement appeared to be weakening after holding a series of weekly Saturday protests since mid-November.

French President Emmanuel Macron did not specifically refer to the forklift incident, but tweeted his condemnation of the "extreme violence" against "the Republic, its guardians, its representatives and its symbols".

Police said about 3,500 demonstrators turned up on the Champs-Elysees in Paris on Saturday morning.

Some then made their way south of the river to the wealthy area around Boulevard St Germain, where they set light to a car and several motorbikes and set up burning barricades, prompting police to fire tear gas to try and disperse them.

Police said 35 people were arrested.

Nationwide protests

As many as 2,000 people were in Rouen, northwest of Paris, where some set up burning barricades. One protester was injured and at least two others were arrested, police said.

About 4,600 protesters hit the streets of the southwestern city of Bordeaux, with some hurling stones at police who answered with tear gas and water cannon.

Five police were hurt and 11 people arrested, local authorities said, adding several cars were torched and shop windows broken.

Further south in Toulouse, 22 people were arrested following clashes that erupted after 2,000 people turned out to demonstrate.

And in the central-eastern city of Lyon, several thousand took to the streets, blocking access to the A7 motorway and causing traffic jams for those returning from Christmas holidays in the mountains.