Four are placed under formal investigation in France for suspected links to the Paris split attack

French authorities have charged and detained four Pakistanis suspected of links to a meat-splitting attack by a compatriot outside Charlie Hebdo’s former office every week who injured two people, the National Prosecutor’s Office said on Friday.

The four male suspects, aged 17 to 21, were in contact with the attacker, says a source who is familiar with the case.

They are suspected of having been aware of the attacker’s plan and encouraged him to carry it out, according to another legal source close to the investigation.

Three of them were accused on Friday of having participated in a terrorist conspiracy and were detained. The fourth had already been charged on Wednesday.

Two were arrested in the Gironde department southwest, a third in the northern port city of Caen and the last in the Paris region.

“They share his ideology and one of them expressed his hatred of France a few days before the action,” said one source.

The news of the allegations comes two days after a court in Paris sentenced 13 accomplices of jihadist armed men who massacred Charlie Hebdo’s staff in January 2015.

To mark the beginning of the trial in early September, the newspaper had in typical provocative style reprinted cartoons of the Prophet Mohammed.

Three weeks later, a Pakistani man injured two people outside the week’s previous office and hacked at them with a cleft.

The attacker, known as Zaheer Hassan Mahmoud, 25, was arrested after September’s attack on terrorist charges and remains in custody.

He told investigators that before the attack he had seen “videos from Pakistan” about the satirical newspaper’s decision to republish the cartoons.

>> Another attack on press freedom in France? Paris rolls from stinging

On October 16, a young Chechen refugee teacher beheaded Samuel Paty, who had shown some of the caricatures to his students.

Less than two weeks later, three people were killed when a young Tunisian who had recently arrived in Europe was stabbed to death at a church in the Mediterranean city of Nice.

President Emmanuel Macron’s government has introduced legislation to address radical Islamist activity in France, a bill that has provoked anger and protests in some Muslim countries.