Armed police have raided a flat in the north Paris suburb of Saint Denis in an operation linked to Friday's attacks.
Jordan's King Abdullah II warned of a "third world war against humanity", describing the Islamic State group as "savage outlaws of religion" in the wake of the Paris attacks.
French security sources say that surveillance video shows a possible ninth assailant during Friday's attacks in which 129 people died.
The hacker group Anonymous claim to have taken out 5,500 Twitter accounts linked to the Islamic State group, which claimed responsibility for the Paris attacks.
The Great Mosque of Paris urges French Muslims to gather at the country's most important mosque Friday to say "No to terror" and "We are all Paris!".
Islamic State militants are trying to develop the ability to launch deadly cyber-attacks on UK targets such as air traffic control or hospitals, Chancellor George Osborne says.
Islamic State in a video threatens to attack Washington warning that the countries taking part in air strikes against Syria would suffer same fate as France.
France launches "massive" air strikes on the Islamic State group's de-facto capital in Syria, destroying a jihadi training camp and a munitions dump in the city of Raqqa, where Iraqi intelligence officials say the attacks on Paris were planned.
The owner of a passport found near the body of a suicide bomber in the attacks on Paris passed through a migrant corridor known for its lax controls and ease in obtaining transit documents as a flood of asylum-seekers surges toward Western Europe.
United Nations Secretary-General Ban Ki-moon and UN Security Council condemn the attacks in Paris that killed at least 140 people.