John Lichfield: The government's clumsy response has only encouraged the copycats

The internally divided government, whose clumsy response has helped to fan the flames of protest, attempted belatedly yesterday to satisfy some of the demands of the original rioters. But the violence - involving gangs of 50 to 100 youths burning cars and buildings, including garages, warehouses and a school - has moved on like a bush fire to other poor suburbs.

The motives of the most recent rioters seem to be a generalised anger against the police and the alleged anti-Arab and black racism of French society but - most of all - a desire not be outdone by their rival, neighbouring gangs. Internal security services fear the contagion may spread to other urban areas in France in the next few days.

The riots began, on a limited scale, in Clichy-sous-Bois, north-east of Paris, last Thursday after two teenage boys were electrocuted in a power substation. The boys, aged 15 and 17, were running away from a police identity check, but it remains unclear whether they were being pursued by police when they climbed an 8ft wall protecting a high-voltage electrical transformer.

Friends and companions insist that police officers knew that the boys were in mortal danger, but did nothing to help them. Local anger was fuelled by government statements - later withdrawn - which suggested that the boys may have been responsible for a burglary or vandalism.

The Interior Minister, Nicolas Sarkozy, further inflamed tempers by seeming to describe all young people in poor suburbs as racaille (scum). He later made it clear he meant only the violent, criminal gangs (to which the two dead boys did not belong). The Prime Minister, Dominique de Villepin - M. Sarkozy's deadly rival in the run-up to the 2007 presidential election - allowed his Interior Minister to seize the initiative but has privately encouraged public criticism of his colleague by other members of the government.

The authorities finally attempted yesterday to present a united front and deal seriously with the electrocution incident which sparked the riots. A criminal investigation will consider possible charges against "x", or persons unknown, for "failing to help people whose lives were in danger". This implies that police officers may have been aware that the boys had fled into the electricity station - something still officially denied by the government.