French police raided 168 locations across the country and arrested 23 people as authorities identified more members of a sleeper cell said to be behind the Paris terror attacks.

French and Belgian jihadis - and at least one potential Syrian member - are being implicated in what was the worst attack on French soil since World War II.

The mastermind is said to be a Belgian national linked to thwarted earlier attacks on a train and a French church.

With France under a state of emergency that gives police special powers, the hunt continued for members of the cell that carried out last Friday's gun and bomb attacks.

French interior minister Bernard Cazeneuve said police arrested 23 people and recovered a Kalashnikov and other weapons during the overnight raids.

Heavily armed Belgian police also launched a major operation in the Molenbeek neighbourhood of Brussels, which authorities consider to be a focal point for extremists and fighters going to Syria from Belgium.

Across France and throughout Europe, people paused for a minute's silence at noon French time (11am GMT) in memory of the victims.

Overnight, France launched its heaviest air strikes yet on Islamic State's de-facto capital in Syria. Prime Minister Manuel Valls said 'we are at war' against terrorism.

French authorities said Sunday night's air strikes destroyed a jihadi training camp and a munitions dump in the city of Raqqa, where Iraqi intelligence officials say the attacks on Paris were planned.

Twelve aircraft including 10 fighter jets dropped a total of 20 bombs in the biggest air strikes since France extended its bombing campaign against the extremist group to Syria in September, a Defence Ministry statement said.

The jets launched from sites in Jordan and the Persian Gulf, in co-ordination with US forces.

Three teams of attackers, including seven suicide bombers, attacked the national stadium, the concert hall and nearby nightspots on Friday. In addition to those killed, the attacks wounded 350 people, 99 of them seriously.

French authorities have identified several suspected attackers, most with links to France or Belgium.

A French official identified the suspected mastermind as Belgian Abdelhamid Abaaoud, who is said to be linked to the thwarted attacks on a Paris-bound high-speed train and a Paris area church earlier this year.

The Paris prosecutor's office said that one of the suicide bombers who blew himself up in the Bataclan music hall Friday night was Samy Amimour, a 28-year-old Frenchman charged in a terrorism investigation in 2012.

Amimour was placed under judicial supervision, but dropped off authorities' radar in 2013 and an international arrest warrant was issued.

An attacker who blew himself up outside the national football stadium was said to have been found with a Syrian passport with the name Ahmad Al Mohammad, a 25-year-old born in Idlib.

The prosecutor's office said fingerprints from the attacker match those of someone who passed through Greece in October.

Another, said to have been identified by the print on a recovered finger, was 29-year-old Frenchman Ismael Mostefai, who had a record of petty crime and had been flagged in 2010 for ties to Islamic radicalism.

A judicial official said police have also identified two other suicide bombers, both French nationals who had been living in Belgium: 20-year-old Bilal Hadfi, who detonated himself outside the Stade de France; and 31-year-old Brahim Abdeslam, who blew himself up on the Boulevard Voltaire.

At least one key suspect is on the loose. The arrest warrant for 26-year-old Salah Abdeslam - brother of bomber Brahim - describes him as very dangerous and warns people not to intervene if they see him.

Police already had him in their grasp early on Saturday, when they stopped a car carrying three men near the Belgian border.

By then, hours had passed since authorities identified Abdeslam as the renter of a Volkswagen Polo that carried hostage takers to the Paris theatre where so many died.

Three French police officials and a top French security official confirmed that officers let Abdeslam go after checking his ID.

Islamic State has claimed responsibility for the attacks. Its statement mocked France's air attacks on suspected IS targets in Syria and Iraq, and called Paris 'the capital of prostitution and obscenity'.

Meanwhile, Paris remains on edge amid three days of official mourning. French troops have deployed by the thousands and tourist sites remain shuttered in one of the most visited cities on Earth.

Panic ensued on Sunday night as police abruptly cleared hundreds of mourners from the famed Place de la Republique square, where police said firecrackers sparked a false alarm.

'Whoever starts running starts everyone else running,' said Alice Carton, city council member who was at the square. 'It's a very weird atmosphere. The sirens and screaming are a source of fear.'