By John Irish and Pascal Rossignol
AMIENS, France (Reuters) - Youths jeered and jostled France's interior minister on Tuesday in the northern city of Amiens when he promised to restore law and order at the scene of overnight riots in which police were fired at with buckshot and pelted with missiles.
President Francois Hollande said the state would "mobilize all its resources to combat this violence", which has shaken depressed quarters of major French cities at regular intervals over the past decade.
Police and emergency officials in Amiens were on high alert on Tuesday evening and some, speaking on condition of anonymity, said they feared a further flareup of violence.
Unrest is often blamed on a combination of poor job prospects, racial discrimination, a widespread sense of alienation from mainstream society and perceived hostile policing.
A crowd of about 100 young men met Interior Minister Manuel Valls when he arrived in Amiens to discuss two nights of violence apparently sparked by tension over spot police checks on residents.
"Calm down! Calm down!" Valls yelled as the crowd jostled him while he entered the town hall surrounded by bodyguards.
Valls said 17 police officers were hurt in the rioting, some hit by shotgun pellets, others by a hail of objects thrown by around 100 youths gathered in the city's northern districts.
"Firearms! Can it be considered normal that people turn firearms on police? It's unacceptable ... law and order must be restored," Valls told a news conference, adding that a minority of people were terrorizing the local community.
One officer was in serious condition, the city's Socialist Mayor Gilles Demailly told Reuters.
Hollande, who ordered Valls to break off their joint visit to southeastern France and travel to Amiens, said too little money had been put into security in recent years.
"Our priority is security which means that the next budget will include additional resources for the gendarmerie and the police," he said.
The unrest was the first major law and order test for Hollande's Socialists since his May election victory over conservative incumbent Nicolas Sarkozy, whose tough policies on crime and immigration some critics said fanned urban unrest.
Ahmed, a 27-year-old jobless man who refused to give his family name, revealed the sense of anger some locals felt.
"Yesterday our little brothers did a good job," he said. "Imagine if we got involved, then it would get serious. It's a shame nobody got killed yesterday."
The interior ministry sent reinforcements to Amiens, part of which was already classified as a "priority security zone" in need of extra policing. The policy formed part of the Socialists' election campaign pledge on law and order.
Riot police and gendarmes sat in two dozen vans parked in the northern neighborhood where a recent face-lift included the building of a gymnasium, swimming pool and cultural centre.
One resident, a taxi driver who gave his first name as Jonathan, called the perpetrators "a bunch of idiots."
"It's a game for them and will happen again. It's just to cause trouble, because they are hurting their own people," he said, blaming the riot on weak policing in recent years.
"It was a 'no man's land' and now they want to put in a big police presence. That will only provoke them," he said.
The immediate cause of the two days of disturbances appeared to have been a police spot check on Sunday on a person on the sidelines of a funeral of a young man killed in a road accident.
During a night of violence, rioters set fire to a number of vehicles, in some cases hauling the drivers out of their cars before burning them, mayor Demailly said.
A nursery school was among the buildings gutted in the riot, and a handful of burnt-out cars littered the streets late into Tuesday, though the area was otherwise calm. No one has been arrested so far.
Valls, a law and order hardliner who annoys some fellow Socialists, said there had been other cases this month of "urban guerrilla" behavior.
Mayor of a racially mixed suburb before being appointed to Hollande's government, Valls was a spokesman a decade ago for Socialist Prime Minister Lionel Jospin, whose 2002 presidential election defeat was put down partly to his image as soft on law and order.
France has been rocked by bouts of rioting on a number of occasions in the past decade.
Weeks of rioting in 2005, the worst urban unrest in France in 40 years, led to the imposition of a state of emergency by the then centre-right government in which Hollande's predecessor Sarkozy was interior minister.
Incidents involving police were the triggers for disturbances in 2007 and 2010.
The repeated bouts of violence have provoked agonized debate over the grim housing estates that ring many French cities and the integration of millions of poor whites, blacks and North African immigrants into mainstream society.
(Additional reporting by Jean-Francois Rosnoblet, Brian Love and Daniel Flynn; Writing by Brian Love; Editing by Tim Pearce)