Hundreds of French militants in Syria

France’s Prime Minister says over 800 French citizens or residents have taken part in the fighting in Syria or are planning to do so.

In an interview with BFMTV news channel on Tuesday, Manuel Valls said the number of its nationals who have been fighting or plan to fight alongside the foreign-backed militants in Syria is more than what was previously estimated.

Earlier assessments had reportedly put the number at 300 to 400.

The French premier also warned that the militants operating inside Syria pose an unprecedented security threat when they return home.

“We have never before faced a challenge of this kind. It is without any doubt the most serious threat we face,” Valls said.

The warning followed the recent arrest of Mehdi Nemmouche, a Frenchman with ties to the militants in Syria, on suspicion of carrying out a deadly shooting at the Jewish museum in Brussels on May 24. Paris Prosecutor Franswa Molin said police arrested Nemmouche in the southern French port city of Marseille as he arrived from the Dutch capital, Amsterdam, by bus.

Western officials are concerned that the militants, who have obtained military skills in Syria, would return to their countries and conduct terrorist attacks on home soil.

Syria has been gripped by a deadly crisis since 2011. Several Western countries have played a major role in fanning the flames of the turmoil in the Arab country by arming and training militants.