For months, tear gas clouded the boulevards of Paris most Saturdays as protesters skirmished with riot police, whose heavy-handed response drew condemnation from rights groups.

More that one thousand French "yellow vests" have been sent to prison between last November and the end of June revealed the lastest official estimate by the Public Ministry, as the movement prepared to celebrate its first anniversary on Saturday.

Prison sentences go from a few months up to three years, and an extra group of 1,230 protesters have been sentenced to prison on parole, while 900 have been sentenced to other punishments like community service, reported the Ministry of Justice earlier in November, for a total of 3,000 sentences pronounced during that period of time.

The first major protest against the cost of living by people clad in the high-visibility jackets took place on November 17, 2018 in the form of roundabout blockades around the country.

The movement then morphed into a series of protests with heavy presence of militarized police clashing with demonstrators in Paris, especially the iconic Champs Elysees, serving as the main battleground.

The protests went on to rattle President Emmanuel Macron's government, forcing 15 billion euros in tax concessions after months of citizens' consultations.

The movement will celebrate its first birthday on Saturday, and various protest actions are slated to take place around the capital.

From its peak, during which 300,000 people across France took part in their Saturday protests, turnout has shrunk dramatically in recent months, partly because the violent police repression and a new anti-riot bill voted in Congress is detering protesters to take to the streets.

Sociologist Albert Ogien said in an interview with Reuters that the falling numbers are misleading as support for many of the "gilets jaunes'" key demands is still running high in France, and the government is scared of a resurgence.

"Only by seeing how the ghost of the 'yellow vests' are haunting the government today although there is no one in the streets... we see that it leaves a deep mark," Ogien said. "That's one of the foremost effects that we don't emphasize enough - the government's fear."

France's unions are planning a robust response to Macron's plans for major reform to the country's pension system with a strike action planned for December 5 across sectors including transport and energy.

And on Thursday, thousands of health workers, many of whom have been striking for eight months, took to the streets of Paris to demand better working conditions and more investment in a system they say is creaking at the seams.

In the early days, the "yellow vests" never fully managed to join forces with traditional trade unions despite shared concerns about the cost of living. But Ogien said that was changing and that they may well swell the ranks of the protests in the upcoming pensions showdown.

"Little by little, this maturing leads us to understand that the demands that we have were what the unions have been fighting for. Why have two camps?" he said.

From their deliberately apolitical beginnings, some "yellow vests" are also organising into more overtly political structures, Ogien added, and may one day form a popular party reminiscent of Spain's Podemos.

"We need to work on the demands that we have on the table," he said. "We need a political maturity."

A survey by pollster Odoxa published two weeks ago showed nearly one in every two French people believed the “yellow vest” movement might reawaken.