Remy Daillet, a French far-right conspiracy theorist, has been charged with a terrorist offence and for planning violence and attacks against the state.
Remy Daillet, 54, was arrested in June after returning from years abroad. He was initially charged over the kidnapping of an eight-year-old girl from her grandmother's house earlier this year, allegedly organised from afar by Daillet at the mother's request.
But a judge on Friday charged him with terrorist conspiracy, months after an investigation was opened into a shadowy group known "Honneur et nation" (Honour and Nation).
The group - 12 suspects - is accused of plotting a series of attacks, including an attack against vaccination centres, a masonic lodge, prominent people and journalists, according to sources close to the case.
The team had "a multitude of violent actions planned, targeting institutional sites, vaccination centres, 5G antennas...," one source familiar with the case had said earlier.
Daillet has called for a ban on face masks which he claimed were "scientifically useless" in videos and for 5G networks to be destroyed.
Another source had said the suspects had "the idea of a coup d'etat, of an overthrow of the French government".
Daillet's lawyer Jean-Christophe Basson-Larbi labelled his client a "political prisoner" who had spread only non-violent political ideas.
After the girl's abduction, Daillet posted a video denying kidnapping, saying that his organisation "returns children kidnapped by the state to parents, at their request".
French prosecutors in April issued an international arrest warrant for Daillet, who had been living in Malaysia for several years.
He had been a regional leader of France's centrist MoDem party before being dismissed from the party in 2010.