Hundreds of firefighters were battling blazes across southern France on Monday, with one inferno spreading across 900 hectares of forest and threatening homes on the island of Corsica, emergency services said.

The biggest fire was in the village of Bastidonne, in the Vaucluse region, where fires, intensified by strong winds, consumed some 600 hectares of forest.

About 100 residences were evacuated in the village of Mirabeau and a dozen of horses in a stable were also moved to safer ground.

Part of the A51 highway and the railway line between Briançon and Marseille have been closed temporarily, and public access to several forest areas has been suspended, prefecture officials said.

"The fire is very fierce and heading to urban areas of Biguglia," lieutenant-colonel Michel Bernier, of France's civil defence forces, told AFP news agency.

The blaze engulfed a sawmill and burned 10 vehicles.

There were also forest fires in Corsica, in the city of Carros close to Nice and in the resort town of Saint-Tropez, authorities said.

A prefecture spokesman said that early Monday evening the fires were not yet under control but the situation was evolving favorably as weather conditions were improving.

"We are awaiting reinforcements," regional deputy fire chief Jean-Jacques Peraldi said. Around 160 people were battling the blaze aided by more than a dozen fire engines.

Local official Gerard Gavory said that three firefighting planes were also involved, and "have been surveying the area to make sure no homes are affected."

Another fire on the south of the island, which destroyed 110 hectares around the town of Aleria, was brought under control on Monday, Bernier said.