As the nation prepared to mourn the victims with a minute of silence today, French police released a photograph of a suspect also wanted in Belgium where it is suspected the attacks may have been planned.
In the first strikes since Friday's carnage which killed at least 129 and wounded more than 350, French warplanes bombed IS targets in Raqa, the Islamists' de facto capital in Syria. The raid destroyed an IS command post, jihadist recruitment centre, a munitions depot and a "terrorist" training camp, the defence ministry said.
The operation was conducted in coordination with US forces by a dozen aircraft which took off from Jordan and the United Arab Emirates, it said. President Francois Hollande has denounced the Paris attacks -- the worst in the country's history -- as an "act of war" and vowed to hit back against Islamic State "without mercy".
French police said they were seeking a "dangerous" suspect, 26-year-old Salah Abdeslam who is said to be one of three brothers linked to the slaughter. He is believed to be either on the run or one of the gunmen who died during the attacks, security sources said.
He lived in the poor immigrant Brussels neighbourhood of Molenbeek, where Belgian police made several arrests in connection with the Paris attacks. "We are determined to act together... to dismantle the networks" of the jihadists, French Interior Minister Bernard Cazeneuve said after talks yesterday with his Belgian counterpart Jan Jambon.
As the investigation spread across Europe, police last evening carried out a search in Bobigny, in the northern suburbs of Paris, but the results were not yet known. Prosecutors said they believed three groups of attackers were involved in the carnage, and they did not rule out that one or more assailants may still be at large.
The heavily armed gunmen wearing explosives vests opened fire on crowds enjoying a Friday night at outdoor cafes and at the Bataclan concert hall, scene of the worst carnage where 89 people were killed as they watched a gig by the Eagles of Deawarplanesth Metal group.
Seven of the gunmen and suicide bombers died in the bloodshed, with three blowing themselves up outside the Stade de France as the French and German football teams were playing a friendly.