France and Belgium staged dozens of raids on suspected extremists on Monday as Paris struggled back to its feet and the prime minister steeled the nation for more bloodshed after its deadliest ever terror attacks.

A traumatised nation stopped for a minute's silence at midday (1100 GMT) to honour at least 129 people killed in the unprecedented assault on Paris nightspots and the national stadium.

Thousands paused in the streets and President Francois Hollande observed the silence at the Sorbonne University, in recognition of the large number of young victims.

In Place de la Republique, close to the Bataclan concert hall which suffered the worst bloodshed, 55-year-old caretaker Kenza wept as she reflected on the carnage that took place 200 metres away.

"My daughter was there just two minutes before it happened. My thoughts are with all the mothers who lost children," she said.

Investigators identified two more attackers involved in the attack, including a Frenchman previously charged with planning a terror attack and a suicide bomber found with a Syrian passport, although the document's authenticity has yet to be verified.

Police conducted "several dozen" raids across France while Belgian police launched a new operation in a radical hotspot where some of the attackers are thought to have lived.

- Rocket launcher -

In the southeastern French city of Lyon, police found "an arsenal of weapons," including a rocket launcher and Kalashnikov assault rifle.

More than 100 people have been placed under house arrest, 23 arrested and 31 weapons seized, Interior Minister Bernard Cazeneuve said.

As authorities scrambled to find those responsible, the grieving French tried to return to the humdrum of daily life.

Mountains of flowers and candles have been laid at the scenes of the attacks and in front of businesses that lost loved ones.

"We need to understand how this barbarism can exist and why France is paying this heavy price," David Boy, a 52-year-old advertising agency boss said, his lips trembling as he lingered at one of the memorials on his way to work.

Metro trains were packed with commuters, pupils returned to schools and museums reopened, although a national state of emergency remained in place.

Culture minister Fleur Pellerin said a special fund would help get live entertainment back on its feet and help with the cost of new security measures, while a social media campaign has called on everyone to visit cafes and bars on Tuesday night.

In the face of "barbarism... culture is our biggest shield and our artists our best weapon," said Pellerin.

The rector of the Great Mosque of Paris, Dalil Boubakeur, called for all French imams to lead "a solemn prayer" for the victims on Friday.

Prime Minister Manuel Valls said Friday's attacks were "planned from Syria" and warned more could follow.

"We know that operations were being prepared and are still being prepared, not only against France but other European countries too," he told RTL radio.

Late on Sunday, French planes bombed the stronghold of the Islamic State jihadists, who claimed responsibility for Friday's carnage.

French jets hit an IS command post, a recruitment centre, a munitions depot and a training camp in Raqqa, northern Syria, and more raids were reported on Monday.

- The Belgian connection -

Much of the investigation's focus has swung to Belgium.

French Interior Minister Bernard Cazeneuve said the attacks were "prepared abroad and involved a team situated on Belgian territory and who may have benefited from... complicity in France."

Police released the photo of 26-year-old Salah Abdeslam, one of the three brothers linked to the attacks, who is thought to be on the run.

One brother blew himself up in the Bataclan and was identified from a severed finger, while the third was arrested in Belgium but released without charge.

The brothers lived in the rundown Brussels neighbourhood of Molenbeek, which has a reputation as a hotbed of Islamic militancy and where police have made several arrests.

Five of seven known attackers have been identified, but it is unclear if other gunmen involved fled after the attacks which are believed to have been carried out by three teams.

Two of the gunmen behind the bloodbath at the Bataclan theatre, where 89 people were killed, have been identified as 29-year-old Paris native Omar Ismail Mostefai and 28-year-old Samy Amimour.

A Turkish official said police there had twice warned France about Mostefai, who was one of 10,000 people tagged by French intelligence as having been radicalised.

Amimour was charged in France in 2012 for "conspiracy to commit terrorism" over a foiled plot to carry out an attack in Yemen.

He violated his judicial supervision in 2013, prompting judges to issue an international arrest warrant.

One attacker at the Stade de France national stadium, where three blew themselves up outside the stadium during a match, was carrying a Syrian passport in the name of Ahmad Al Mohammad.

The document has yet to be verified and Serbia detained a migrant on Monday whose passport contained the same data.

There are fears some of the assailants entered Europe as part of the huge influx of people fleeing Syria's civil war. Far-right French leader Marine Le Pen has already called an "immediate halt" to the intake of migrants.

The worst terror attack in French history comes less than 11 months after jihadists struck satirical magazine Charlie Hebdo and a Jewish supermarket, killing 17.

IS claimed it had attacked Paris in revenge for the French campaign of air strikes in Syria and threatened further violence in France "as long as it continues its Crusader campaign".

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