The poor suburbs of Paris were set ablaze in the worst of eight consecutive nights of rioting, with 500 cars torched and a gym and primary school razed.

Police today reported that the wave of unrest has now spread to at least 20 provincial towns.

An army of 1,300 police reinforcements moved into the bleak estates of the north-east of Paris last night, to enforce a belated pledge by Dominique de Villepin, the Prime Minister, to stop the rioting that has engulfed the largely Muslim ghettos.

Despite hopes that Eid-ul-Fitr, the festivities ending the fasting month of Ramadan, would calm the unrest, police reports suggest an escalation in what the police union has described as a "civil war"..

Gangs of youths armed with bricks, sticks and petrol canisters spilled through the streets of high-rise housing estates, torching buses and hurling rocks at trains. At least 80 arrests were made in fierce clashes with the massed ranks of riot police.

According to one report, a disabled woman was doused in petrol and set alight when she was unable to escape a bus under attack in the northern suburb of Sevran. She was rescued by the driver and is being treated for severe burns.

Disturbances also took place for the first time in other towns, including Rouen, Marseille and Dijon..

Television networks have mostly stayed away from the scenes of the confrontations. Camera crews have been physically attacked and reports blamed for stoking the discontent.

"Why a school, why a car? What can you say about such blind violence," said Michel Beaumale, mayor of Trappes, southwest of Paris, outside the smouldering ruins of a local primary school.

Francis Masanet, leader of the UNSA police union, said: "It is very serious and we fear that events could get worse."

The warfare of the streets, initially triggered by the deaths of two African teenagers who ran into an electricity relay station fearing they were being chased by police, has flared into broader protest against the living conditions and prospects of African communities.

It has been played out against a backdrop of political bickering between the Prime Minister and Nicolas Sarkozy, the interior minister and his rival for presidency in 2007. M de Villepin has been accused of leaving his rival to deal with the fallout from the unrest.

M Sarkozy's hard-line stance - he has spoken of "hosing down" the "scum" - has fanned the flames of protest, and may have damaged his future prospects for the presidency. It has also exposed a philosophical split in the Cabinet and country over the place of immigrants in French life, and caused policies of integration dating back 30 years to be re-examined.

Evidence of the scale of law-breaking, in what are officially known as "les quartiers difficiles", came with a police report yesterday that 28,000 vehicles had been torched in outbreaks of urban violence in France so far this year.

Unemployment among French men aged 15 to 24 has risen from 15 per cent four years ago to more than 22 per cent. It is thought to be as high as 30-40 per cent among young second- and third-generation immigrants in poorer high-rise suburbs.

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