On a visit to Crépol, a village of around 500 people in the Drôme area of southeastern France. government spokesman Olivier Véran made an appeal to people "not to answer violence with violence" and warned that society was at risk of "tipping over".

In France, four southern regions - the Rhone, Drome, Ardeche and Haute-Loire - were placed under red alert, the country's most serious warning.

The departments targeted by the alert, which allows local authorities to call off events and close public facilities if needed, are the Rhone, Drome, Ardeche and Haute-Loire, Meteo France said.

The departments that will be targeted by the alert are the Rhone, Drome, Ardeche and Haute-Loire, Environment Minister Christophe Bechu told reporters.

Temperatures are expected to rise to between 40 and 42 Celsius on Tuesday afternoon in the southern departments of Ardeche, Drome, Vaucluse and Gard, Meteo France said.