France's interior minister has warned rioters of stiff jail sentences for arson after a ninth night of violence in African and Arab communities.
The deaths of two teenagers of African origin triggered the unrest
Nicolas Sarkozy said setting cars on fire could "cost dear in terms of sentences" after a night which saw nearly 900 vehicles damaged.
He said the government was "unanimous about standing firm" against violence.
More unrest was reported on Saturday, with arson attacks in Essonne near Paris and Toulouse in the southwest.
Firefighters were called in to deal with a number of burning vehicles, two schools and a paper recycling facility outside the capital.
There were eight incidents involving cars in the southern city, France's fourth largest.
Earlier hundreds of people joined marches in Paris suburbs to protest against the violence.
In Aulnay-sous-Bois, which has seen some of the worst of the rioting, residents walked past burnt out vehicles and buildings with banners reading "No to violence" and "Yes to dialogue".
The suburb's mayor, Gerard Gaudron, appealed for calm outside a fire station which had come under attack.
But youths at the rally in the suburb's rundown Mitry estate predicted violence would continue until Mr Sarkozy resigned.
Later Prime Minister Dominique de Villepin met eight key ministers and the head of the Paris mosque, Dalil Boubakeur.
After the meeting, Mr Boubakeur urged a change in tone from the government.
"What I want from the authorities, from Mr Nicolas Sarkozy, the prime minister and senior officials are words of peace," he said.
Mr de Villepin has been holding a series of meetings with public figures and ordinary people from the affected areas as he seeks an end to the crisis.
Unrest began after the deaths of two youths in a rundown suburb of Paris.
Bouna Traore, 15, and Zyed Benna, 17, were accidentally electrocuted at an electricity sub-station in Clichy-sous-Bois after reportedly fleeing from police in an incident now being investigated.
Police arrested more than 250 people on Friday night as arsonists attacked nurseries and a school and unrest spread to Nice, Lille, Marseille and Toulouse.
Mr Sarkozy's much-quoted description of urban vandals as "rabble" (racaille) a few days before the riots began is said by many to have already created tension.
Reports of a police tear gas grenade hitting a mosque during the riots further inflamed feelings.
During Friday night's unrest rioters tended to avoid direct clashes with police, but arson attacks were widespread:
- Two nurseries, one in Yvelines and another in Bretigny-sur-Orgeand, were set on fire along with a school in Seine-et-Marne, the French news agency AFP reports
- A blaze in an underground car park in Suresnes, Hauts-de-Seine, left at least 36 vehicles destroyed
- An emergency services vehicle was attacked and burnt out in Meaux, Seine-et-Marne
- Several car torchings were reported in the cities of Dijon, Marseille and Rouen, as were violent attacks in Nice, Lille and Rennes.
Clichy-sous-Bois: Two teenagers die in electricity sub-station on 27 October. Successive nights of rioting follow rumours they were fleeing police. A number of people arrested or injured.
Aulnay-sous-Bois: A flashpoint after violence spread from Clichy. Shots fired at police and cars and shops set ablaze. Further trouble in eight nearby suburbs, with more shots fired at police.
Elsewhere in Paris: Reports of incidents in towns in the suburban departments of the Val-d'Oise, Seine-et-Marne and Yvelines. Reports of petrol bombs thrown at a police station in the Hauts-de-Seine.
Elsewhere in France: Rouen, Lille, Toulouse, Nice and Marseille all see violence on Friday night.