Two firefighting planes have been rushed to the Paris region to tackle a large wildfire south of the French capital.
The Fontainebleau forest blaze, described by officials as "virulent" and of "exceptional scale", partially closed the country's main north-south highway, disrupting traffic during the first major weekend getaway of the summer.
Early on Monday, officials said the fire had raced across 800 hectares and was still spreading in the forest, about 40 miles (60km) south-east of the city of Paris.
The Paris region is suffering through its third heatwave this year during a summer in which temperature records have broken in several countries across Europe.
It was the first time firefighting planes had been sent up from the normally drier and hotter south of the country to tackle fires in the Paris region, Eric Brocardi, of France's national federation of firefighters, said.
Two firefighting helicopters and an observation aircraft had also been deployed, he added, according to Agence-France-Presse.
"The aim is to save lives and property," he was quoted as saying.
Earlier, a fire had also blocked a highway running east from Paris and disrupted a high-speed train line to the south of France.
Travellers were facing delays of up to six hours for trains arriving at or leaving from Paris's Gare de Lyon, French rail company SNCF said on Sunday evening.
The latest French heatwave has forced the temporary shutdown of three nuclear power stations to avoid the discharge of warm cooling water into overheated waterways.
Organisers of the Tour de France cycling race also shortened Sunday's stage by 30km (19 miles) as temperatures neared 40C.
The record-breaking temperatures across Europe this summer have led to major wildfires, most notably in Spain where at least 13 people were killed by Thursday's wildfire in Almeria, one of the country's deadliest ever.
And in the UK, a large wildfire in north Wales was declared a major incident by emergency services on Sunday, as firefighters tackled fires across England and Wales.
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