A huge manhunt is under way for surviving members and accomplices of the Islamist group that killed 129 people in Paris on Friday night.
Police have named Brussels-born Salah Abdeslam, 26, as a key suspect. He was reportedly stopped by officers in the wake of the attacks - but then let go.
Meanwhile, French aircraft have attacked the Syrian stronghold of IS.
Latest reports from France say police investigating the assaults have carried out a raid in a Paris suburb, Bobigny.
French media organisations say major police operations have also taken place in Jeumont, close to the French border with Belgium, and in the southern city of Grenoble - but it is unclear if they are linked to the Paris attacks.