(AFP) - French President Emmanuel Macron met with hundreds of French officials on Tuesday to begin exploring the "deeper reasons" for the country's plunge into riots after a police officer killed a teenager at a traffic stop.

The meeting at the Elysee palace in Paris with more than 300 mayors, whose municipalities suffered damage over a week of violence, came as the unrest eased across the country.

"Is it a permanent return to calm? I will be cautious, but the peak that we've seen in previous days has passed," Macron said, according to a participant.

The government has battled riots and looting since an officer killed 17-year-old Nahel M. during a traffic stop on June 27 in a Paris suburb, rekindling long-standing accusations of systemic racism among security forces.

On Monday night violence in French cities had halved in 24 hours, the interior ministry said, with 72 people arrested nationwide.

- 'Painstaking long-term work' -

At the gathering of mayors, Macron was hoping to "start the painstaking, long-term work needed to understand the deeper reasons that led to these events", an official at the president's office said.

But with right- and left-wing officials pointing fingers at one another and each side insistent on their own solutions, the centrist president said at the end of the meeting that they had failed to find "unanimity".

His government would "reach very real solutions" over the summer, he added, saying "we must strike while the iron is hot".

But Zartoshte Bakhtiari, mayor of Neuilly-sur-Marne east of Paris, said "I came to hear the president give us a vision, set a course. I didn't come for a group therapy session".

Nearly 4,000 arrests have been made since Friday, including more than 1,200 minors, according to justice ministry figures.

Macron suggested fining the parents of children involved.

"With the first crime, we need to find a way of sanctioning the families financially and easily," he said, according to comments reported by the Parisien newspaper.

During the meeting with mayors, Macron also promised to fast-track a new law allowing for rapid assistance with rebuilding damaged buildings, public spaces and vandalised transport infrastructure.

- Rubber bullet death probed -

In the southern city of Marseille, which has seen some of the worst riots, prosecutors announced a probe into the death of a 27-year-old man on Saturday night.

He is believed to have suffered a heart attack after the "violent shock" of a rubber bullet known as a "flashball" that is used by French police hitting him in the chest.

It was not clear if he was participating in the protests or was a passer-by, the prosecution said.

French businesses meanwhile were assessing the cost of seven nights of rioting that left countless shops and other outlets vandalised.

"They destroyed everything," said Alexandre Manchon, who works at a tobacco shop in Marseille.

"None of this is our doing, we are just working people who get up at five in the morning so we can feed our children and families," he told AFP.

Employers' organisations called on the government to create an emergency fund "for those who lost everything".

Finance Minister Bruno Le Maire said Tuesday that the government might allow damaged businesses to suspend tax and social security payments as they rebuild.

But he said the riots would not impact France's ability to attract business or tourists, as the country prepares to host the summer Olympic Games next year.

"The French economy is solid... and the daily life of all French citizens is not threatened by what happened. And we are coming back to a more quiet situation after four or five days of riots," he told CNN television.

Police meanwhile said one of the passengers in the car driven by Nahel M., who had turned himself in, had been questioned to determine the exact circumstances of the shooting.

The policeman who fired the lethal shot remained in custody Tuesday, charged with homicide.

An online collection for the family of the 38-year-old officer, launched by far-right figure Jean Messiha, has gathered more 1.5 million euros ($1.6 million), sparking outrage in particular among the political left.

Messiha said on social media he was closing the collection Tuesday at midnight, while the family of Nahel M. said it had filed a legal complaint over the fundraising move.

A fund to support the family of Nahel has run to just under 346,000 euros.

© Agence France-Presse