The northern French city of Amiens on Wednesday began a costly clean-up after two nights of rioting that left France again asking itself what to do about marginalised urban neighbourhoods that have regularly erupted into violence in the past decade.

• 'Quiet night' in Amiens after riots (15 Aug 12)
• Hollande vows to fight the riots (14 Aug 12)
• Violent riots in Amiens leave 16 officers injured (14 Aug 12)

The city's northern quarter was calm overnight, 24 hours after rampaging youths torched cars and public buildings, hurled explosives improvised from

fireworks and fired buckshot at police.

France's Interior Ministry announced Wednesday that a heavy police presence would be maintained in the neighbourhood for several days to ensure there was no repeat.

Around 250 officers were deployed overnight following clashes in which 16 officers were injured, one of them seriously.

"The reinforcements will remain deployed over the next few days and nights to ensure a complete return to normal," Interior Minister Manuel Valls said in
a statement.

Valls promised a crackdown on "troublemakers" would be balanced by attempts to foster a partnership between police and the local community in order to
avoid further conflict.

Gilles Demailly, the mayor of the city some 120 kilometres (75 miles) north of Paris, said the cost of repairing or rebuilding public buildings that were
damaged or destroyed could run to six million euros (about $7.4 million).

The scale of the damage – a sports centre and a primary school suffered extensive fire damage – made the Amiens riot the most serious incident of its
kind since the Villeneuve suburb of Grenoble exploded two years ago.

France's Socialist government has promised a tough response with Valls warning that no amount of social deprivation could excuse firing at police or
burning public buildings.

"The rule of law, order and justice has to be re-established here in Amiens and the police will be given the means to ensure that they are," he vowed.

President Francois Hollande has promised to boost police numbers in some of France's most deprived urban areas and said that the fight against crime will
be spared the cutbacks most government departments face.

Unemployment in the riot-hit part of Amiens runs at 45 percent. Among under-25s, who account for half the population, two out of three are out of
work.

With France's economy stagnating and the jobless total already at a record high, some fear the Amiens violence could be a sign of things to come as
Hollande's government embarks on an austerity programme.

But Didier Lapeyronnie, a sociologist at Paris's Sorbonne University, does not expect the unrest to spread.

"It is not the kind of protest that you get on the left bank in Paris," he told AFP.

"There is an element of social protest but it is not only that. This type of incident tends to happen in areas where there is real tension between a
community and the police. It comes to a head from time to time, often because of a badly-judged intervention by the police."

The unrest in Amiens was triggered by what residents considered to be provocative spot-checks carried out at the time of a funeral for a 20-year-old
who had died in a motorbike accident last week.

Tanazi, a 28-year-old rapper and self-styled spokesman for the neighbourhood, said local youths were fed up with being stopped by police "every day from when you're five years old."

"The CRS (riot police), they think they're in a zoo," he told AFP.

Local police reject the allegation of heavy-handed tactics but have admitted they are struggling to cope with troublemakers in a neighbourhood
described as a "no go area" by the city's mayor.