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

Residents were evacuated from homes at the edge of the town of Biguglia, on the island's northeastern coast.

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