France has asked its EU neighbours for more help fighting fires raging in the south-east.
It has requested two additional Canadair water bombers to add to the 19 aircraft currently battling the flames.
The regional head of security Stephane Bouillon described a fire in La Croix-Valmer near Saint-Tropez, a wealthy resort, as "extremely virulent and difficult to control".
Unusually hot, dry and windy regional weather has added to the problem.
Some 3,000 hectares (11.5 sq miles) of land have burned along the Mediterranean coast, in the mountainous interior and on the island of Corsica.
In Corsica, firefighters worked overnight to tackle flames which consumed a sawmill and several vehicles, and it had been brought under control by Tuesday morning.
Hundreds of homes have been evacuated as the fires threaten resorts during the holiday season.
'Not enough resources'
More than 2,000 firefighters have been deployed across the afflicted area, but one based on the mainland coast told Reuters news agency they were thinly stretched.
"The situation is not under control because we don't have enough resources. The current problem for the department is that there is another fire that has spread more than 150 hectares further north and there are two or three fires which are still active.
"So obviously we have to allocate our resources accordingly. So we will have to wait for the water cannons to arrive."
He added that because the fires had broken out on Monday evening, when aerial services are not operational, the firefighters had endured hours working without aerial help.
Several firefighters were reportedly injured and slightly intoxicated but there were no reports of deaths.