France says it arrested four people linked to a September 25 meat cleaver attack in Paris, outside the former offices of satirical magazine Charlie Hebdo.
The four are of Pakistani origin, as is the main suspect, Agence France-Presse reported.
Two people were wounded in the attack.
According to news reports, the four were arrested Monday, with one being charged two days later with taking part in a terrorist conspiracy. The remaining three were set to be charged, as well.
The four were suspected of knowing about the attack beforehand and encouraging Zaheer Hassan Mahmoud to carry it out, according to a report in the Le Parisien newspaper.
Mahmoud, who said he wanted to attack the magazine for publishing cartoons of the Prophet Muhammad, was arrested after the attack and remains in custody.
Two days before the arrest, a French court convicted 13 accomplices in the 2015 gun attack on Charlie Hebdo offices that killed 12 and wounded 11.
Charlie Hebdo vacated those offices after the 2015 attack and is now in a secret location.
In October, a Chechen refugee in a Paris suburb beheaded a teacher, Samuel Paty, who had shown the Hebdo cartoons to his pupils.