See slide show of violence
Violence has flared for a seventh night in immigrant communities to the north-east of Paris. Youths in several areas have been roaming the streets with sticks, as buildings have been vandalised and dozens of vehicles set alight.
The unrest came after ministers held crisis talks on the situation and the president appealed for calm. Violence broke out following the death of two teenagers. Locals say they were fleeing police, which authorities deny.
On Wednesday night police clashed with youths in nine areas of the Seine-Saint-Denis department - where the violence began last week. A police station was briefly besieged in Aulnay-sous-Bois, and a total of about 40 cars were burnt. Two primary schools, a post office and a shopping centre were damaged and a large car showroom set ablaze in the impoverished neighbourhoods.
The situation also remained tense in the original flashpoint of Clichy-sous-Bois, the BBC's Alasdair Sandford reports from the town. Our correspondent saw a gang suddenly turn on police vans - hurling stones and petrol bombs.
The prime minister and interior minister have delayed trips abroad to try to calm the unrest. When you fire real bullets at police, you're not a 'youth', you're a thug says Nicolas Sarkozy French Interior Minister.
On Wednesday Prime Minister Dominique de Villepin summoned ministers to a meeting, from which no details have emerged. However, he told parliament a disruptive minority should not be confused with the majority of youngsters, who want to integrate. "Let's avoid stigmatising areas," he said.
Correspondents say Mr de Villepin's comments were a rebuke to his political rival, Interior Minister Nicolas Sarkozy, who has called the rioters "scum". Mr Chirac warned earlier of a "dangerous situation". "The law must be applied in a spirit of dialogue and respect," he said.
Dozens of vehicles have been torched and more than 30 arrests have been made since the violence began last week. Unrest flared in Clichy-sous-Bois after two teenage boys of North African origin were electrocuted on Thursday at an electricity sub-station. Local people insist they were fleeing from police and scrambled in to hide. Police say they were not chasing the boys. An official investigation is under way.
Clichy saw five successive nights of confrontation between police and young people from the mainly north African Muslim communities in the north-eastern suburb. Correspondents say anger grew after a tear gas canister was hurled into a mosque in Clichy on Sunday night. Emotions have also been fuelled by mass arrests. Unemployment and social problems are rife in many of France's poorer suburban areas. In recent days there have also been incidents involving groups of youths in other departments near Paris - including the Val-d'Oise, Seine-et-Marne, Hauts-de-Seine and Yvelines.