Jacline Mouraud, a 51-year-old hypnotherapist living in Vannes in the northwest region of Brittany, claims to have received two threatening letters.
She has also complained about videos posted to YouTube that she considers slanderous.
Extracts of videos shown to media feature phrases including “one day, you’ll pay for all your bullshit,” “your ‘Yellow Vests’ are ticking us off” and “Jacline to the butcher”.
“We have received a complaint for threats and slander,” confirmed François Touron, the prosecutor of Vannes, a city in the northwest region of Brittany.
“We will examine the videos and messages she denounces to see if there is evidence of criminal misconduct and to try to identify the authors.”
Sources indicated the complaint was filed on Monday.
Mouraud has been one of the faces of the “Yellow Vests” (Gilets Jaunes) protest movement that has drawn tens of thousands of people to occasionally violent rallies in cities around the country in recent weeks.
She is even cited as a catalyst for the movement due to a video posted to Facebook on 18 October, in which she denounces a proposed carbon tax’s implications for motorists.
The Yellow Vests tend to share the sentiment that the administration of President Emmanuel Macron is contemptuous of their situation.
Macron said he would hold a “major consultation” to respond to the anger, but also affirmed his government would proceed with the carbon tax.