Two young men and a 17-year-old woman will be brought before a French judge Friday as part of the inquiry into the grisly killing of a teacher who showed students cartoons of the prophet Mohammed, judicial sources told AFP.
The three suspects, who were detained Tuesday, face charges of "associating with terrorist criminals" following the death of Samuel Paty near his school in a Paris suburb last month.
Paty, 47, was decapitated by an 18-year-old Chechen who responded to a social media campaign denouncing his use of cartoons re-published by the satirical weekly Charlie Hebdo as part of a class on freedom of expression.
His killing sparked a torrent of outrage that prompted President Emmanuel Macron to crack down on Islamist extremism and violence, in a country that has been hit with a wave of jihadist attacks since 2015 that have killed more than 250 people.
At least one of the two men, both 18, is suspected of having exchange text messages with Paty's killer, Abdullakh Anzorov, who was shot and killed by police after the attack.
They were detained in separate regions of eastern France, one source said, hundreds of kilometres from the Paris suburb of Conflans-Sainte-Honorine where Paty was killed, and from the Normandy city of Evreux in where Anzorov lived.
Seven people have already been charged in the investigation of Paty's murder, including two teenagers aged 14 and 15 accused of pointing out Paty to his killer.
Also charged is a known Islamist radical who helped an outraged father of one of Paty's students stir up a campaign against him via social media.
The father has also been charged, as have three others accused of helping Paty carry out the killing.
Also Friday, prosecutors in the northern city of Cambrai said three more students, aged 15 to 17, were charged with "supporting terrorism" for threats made during a national homage to Paty on Monday.
Similar incidents were reported in several French cities by youths suggesting Paty had got what he deserved for showing the Charlie Hebdo cartoons which angered many Muslims and sparked furious protests in several countries.
Charlie Hebdo had republished the cartoons in September to mark the start of a trial for 14 suspects accused of complicity in the January 2015 massacre of 12 people at the paper's Paris offices by two jihadist gunmen.
Education Minister Jean-Michel Blanquer told RTL radio Friday that some 400 similar incidents during Paty's homage had been reported, "some expressed mildly, others more forcefully".
But legal action is likely in only around a dozen cases, Blanquer said.