French police have arrested four people allegedly involved in a jihadist recruiting network days after they held a 29-year-old Islamist extremist over the deadly shooting at the Jewish Museum of Belgium in Brussels.
French Interior Minister Bernard Cazeneuve said the new arrests were made by security forces carrying out an operation against "people who recruits jihadists" in the Paris region and the south of France.
"We will not give terrorists a chance," Cazeneuve told Europe 1 radio, without providing further details.
French President Francois Hollande pledged to fight home-grown radicals after Mehdi Nemmouche, a 29-year-old alleged Frenchman who spent time in Syria, was detained on suspicion of shooting four people dead at Jewish Museum in Brussels last month.
"The whole government is mobilized to follow the jihadists, and prevent them from being able to cause harm," Hollande said.
Nemmouche was arrested during a customs inspection in the French port city of Marseille, where he arrived on a bus from Amsterdam.
Authorities said he was in possession of firearms, large quantity of ammunition and a video claiming responsibility for the attack that shocked Europe's Jewish community.
One of the weapons was wrapped up in a white sheet scrawled with the name of the Islamic State of Iraq and the Levant (Isis), an Islamist group active in Syria and Iraq, Paris prosecutor Francois Molins said.
Nemmouche also had a portable camera on which detectives found a 40-second video, marked with the Isis logo and including a voice similar to that of the suspect claiming responsibility for the "attack in Brussels against Jews".
Molins said the suspect became radicalized in prison when he was serving time for seven convictions for crimes unrelated to terrorism including an attempted robbery.
A native of the northern French city of Roubaix, on the Belgian border Nemmouche left France for Syria upon release in 2012.
"The new elements in this investigation draws attention once more to the problem of the 'returnees' —in other words the people going to Syria to participate in combat and return afterward to our country," Belgian federal prosecutor Frederic Van Leeuw said.
Two Israeli tourists, a French citizen and a Belgian national were killed in the museum attack.