A French police officer has been detained after shooting dead a driver who failed to obey an order to stop.

Authorities said the driver failed to stop after an officer told him to because he was driving dangerously, in the incident in the southern city of Nice.

Instead, police said, the driver accelerated to flee.

It is the latest in a string of incidents that raise questions about the use of guns by French police.

Nice mayor Christian Estrosi thanked police officers on Twitter.

He wrote: "Full support for @policenat06 agents faced with a refusal to comply on Avenue Henri Matisse. Faced with a driver who deliberately ran over them, they had to use their weapon to neutralise him.

"Refusals to comply are a crime and are on the increase. In the past 24 hours, our @pmdenice has been confronted with two particularly violent refusals to comply. Faced with this upsurge, we must be behind our police."

Deputy prosecutor of Nice, Maud Marty, said at some point the car "turned back to be in front of the police car and rammed into it twice".

She said the officer fired a single shot at the driver.

A video on social media showed the car, in front of the damaged police vehicle, driving backwards while an officer in the street points his gun at the driver's window.

The officer shoots just after the driver appears to stop the car.

Police unions said the officer acted in self-defence.

The latest incident took place in the same week the trial for the 2016 Bastille Day truck attack that killed 86 people in Nice got under way in Paris.

Some experts say the number of deaths caused by officers using their weapons is increasing, with French researcher Christian Mouhanna, from France's National Centre for Scientific Research (CNRS) saying the rise in incidents came after legal changes were introduced in 2017.

The changes were brought in after a series of attacks by extremists in the country in 2015-2016.

In another recent incident in the western city of Rennes, a 22-year-old woman was killed after police opened fire on the car she was in during an anti-drug operation, wounding the driver.

Earlier this year, a French police officer was charged with involuntary manslaughter after shooting dead two men in a car as they sought to escape a police check on the Pont-Neuf bridge in central Paris, on the night of French President Emmanuel Macron's re-election.

News broadcaster France Info said, based on it own count due to the lack of official statistics, nine people have been killed by police in similar situations this year.

Last year, four people were shot dead in such circumstances, according to police figures.