France's interior minister on Monday predicted more arrests of Islamic extremists and warned of possibly hundreds of home-grown militants at large following a crackdown that sent shockwaves through the country's Jewish community.

Manuel Valls issued his warning in the wake of a nationwide sweep at the weekend which left one man dead and 12 others in detention on suspicion of either being involved in the bombing of a Jewish grocery last month or of planning other anti-Semitic attacks.

"We know that there are dozens, even hundreds of individuals who are capable of organising themselves like the group that has just been dismantled," Valls said.