Hundreds more people were evacuated from their homes as wildfires continued to rage out of control in southwestern France, authorities said on Friday.

More than 1,000 firefighters, supported by nine water-bomber aircraft, have been battling since Tuesday to master two blazes fanned by scorching heat, tinder-box conditions and strong winds.

"The situation is still adverse," said the authority for the Gironde department, where the blazes are raging.

The fires have now burnt 7,300 hectares, a total that increased by 2,000 hectares overnight, authorities said.

Another wildfire that broke out near the southeastern town of Tarascon on Thursday and burnt at least 1,000 hectares has been stabilised, according to firefighters.

Wildfires also raged across Portugal, Spain and Croatia, burning homes and threatening livelihoods, as much of Europe baked in a heatwave that has pushed temperatures into the mid-40Cs in some parts.

One of the two Gironde fires was around the town of Landiras south of Bordeaux, where 4,200 hectares have been burnt, roads closed and an extra 480 residents evacuated, bringing the total there to almost a 1,000.

The other blaze, that has already burnt 3,100 hectares, was along the Atlantic Coast close to the "Dune du Pilat" - the tallest sand dune in Europe - in the Arcachon Bay area, above which heavy clouds of dark smoke were seen rising into the sky.

Around 6,000 people were evacuated from surrounding campsites on Wednesday, and another 4,000 people early on Thursday.

Three houses and two restaurants were destroyed overnight in that area, authorities said.