Daillet, 54, and his secretary – identified as 67-year-old Ginette M. – were placed in custody on Tuesday “for planning attacks against the state and other violent action,” including an attack on a Masonic lodge in eastern France, the source said.

Daillet is also alleged to having helped organise the abduction of an eight-year-old girl in eastern France in April at her mother’s request.

He was arrested in June over the kidnapping as he returned to France on a flight from Singapore.

Mia Montemaggi was found safe with her mother in a squat in a disused factory in Switzerland, five days after she was taken from her grandmother’s home in the eastern Vosges region by three men posing as child protection officers.

An anti-terrorist judge had ordered the arrests of Daillet and others as part of an investigation into a shadowy group known as “Honneur et nation” (Honour and nation).

The 12 suspects are accused of plotting a series of attacks, including 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.

Another source had said the suspects had “the idea of a coup d’etat, of an overthrow of the French government”.

Daillet has called for a ban on face masks which he claimed were “scientifically useless” in videos and for 5G networks to be destroyed.

Daillet’s lawyer, Jean-Christophe Basson-Larbi, said on Thursday his client had “no links either with the ‘Honneur et nation’ grouping nor with the planned attacks” or “acts of neo-Nazi terrorism”.

“No objective element points to his involvement,” he said, adding that Daillet was a “political prisoner”.