PARIS, France -- France's prime minister has cancelled a trip to Canada in order to tackle spreading violence in poor Paris suburbs and soothe a public row between his ministers over the government's response.After a sixth night of rioting, Dominique de Villepin on Wednesday summoned eight ministers to a crisis meeting to address the unrest and try to stamp out ministerial squabbling.The unrest has sparked a war of words between Villepin and his deputy Nicolas Sarkozy ahead of 2007 presidential elections.Villepin told parliament he had cancelled plans to leave for Canada on Wednesday. And, while demanding punishment for lawbreakers, he used calmer language than that used by Sarkozy, who had called the protesting youths "scum." "Let's avoid stigmatizing areas .... let's treat petty crime differently to major crime, let's fight all discrimination with firmness, and avoid confusing a disruptive minority with the vast majority of youngsters who want to integrate into society and succeed," he said.Earlier Wednesday French President Jacques Chirac called for calm and warned of a "dangerous situation" in the capital's suburbs."The law must be applied firmly and in a spirit of dialogue and respect," Chirac told a Cabinet meeting Wednesday. "The absence of dialogue and an escalation of a lack of respect will lead to a dangerous situation.""Zones without law cannot exist in the republic," Chirac said. His remarks were passed on to reporters by government spokesman Jean-Francois Cope.The spokesman said Chirac acknowledged the "profound frustrations" of troubled neighborhoods but said violence was not the answer and that efforts must be stepped up to combat it, The Associated Press reported.The unrest, triggered last week by the deaths of two teenagers, spread Tuesday night to at least nine towns in the suburbs north and northeast of Paris as police clashed with angry youths and dozens of vehicles were set on fire.One of the worst-hit suburbs was Aulnay-sous-Bois, where 15 cars were torched and police in riot gear fired tear gas and rubber bullets at gangs of angry youths who threw stones at a firehouse and lobbed Molotov cocktails at a town hall annex, AP reported.In Bondy, 15 cars were burned and four people arrested for throwing stones at police, AP reported officials as saying.Police maintained a tense calm in Clichy-sous-Bois, where the rioting began last week after two teenagers were accidentally electrocuted and a third was injured while apparently trying to escape from police by hiding in a power substation. Officials have said police were not chasing the boys.On Tuesday night, the sixth straight night of unrest, some 150 fires were reported in cars, buildings and garbage bins in the suburbs across the Seine-Saint-Denis region on the north and northeast of Paris, France-Info radio said.The area is home mainly to families of immigrant origin, often from Muslim North Africa, AP said. It is marked by soaring unemployment, delinquency and other urban ills.Police detained 34 people in the overnight violence, Interior Minister Nicolas Sarkozy told Europe-1 radio.Tense battleSarkozy was criticized by government minister Azouz Begag for calling the protesting youths "scum," and the opposition Socialists have denounced Sarkozy's policies.But the interior minister defended his approach."I speak with real words," Sarkozy told Wednesday's Le Parisien newspaper. "When you fire real bullets at police, you're not a 'youth,' you're a thug."Sarkozy described the social aid provided to the suburbs over the years as a failure."We often accepted the unacceptable," he told Le Parisien. "The reigning order is too often the order of gangs, drugs, traffickers. The neighborhoods are waiting for firmness but also justice" and jobs.Sarkozy and de Villepin, both met Tuesday evening with victim's relatives, but the unrest spread even as they met.The two men are locked in an increasingly tense battle to lead the right in the 2007 presidential election.Copyright 2005 CNN. All rights reserved.This material may not be published, broadcast, rewritten, or redistributed. Associated Press contributed to this report.