Nearly 1,000 firefighters backed by water-dropping planes have been deployed to battle a massive blaze in France’s southern Gard region that burned 600 hectares (1,500 acres) overnight.

“This fire is far from being done. There are fronts in hard-to-reach areas that we haven’t tackled and that are advancing freely,” said Lieutenant Colonel Eric Agrinier, a senior member of the fire service, on Friday.

“It’s going to be a feat of endurance,” he added later, warning the blaze may not be brought under control until Sunday because of unfavourable weather conditions.

Working into the night after the blaze began late on Thursday, firefighters set backfires to protect inhabited areas.

“We burn some parts [of the forest] so when the fire spreads it reaches an already-burned zone and slows down, that makes it easier to stop its advance,” said Jacques Pages, standing in front of a line of flames lighting up the pitch-black forest.

Described by emergency responders as a “mega-fire”, the blaze started near the village of Bordezac and forced evacuations from nearby Bessèges and other settlements on Thursday night.

The local prefect’s office said about 100 people had to be put up in holiday homes and restaurants in the area, which is about 90km (55 miles) north of Montpellier and the Mediterranean coast.

“I’ve been finding rooms for people and all the holiday homes are doing the same,” said Regine Marchand, manager of a restaurant in nearby Aujac, on Thursday night.

“We’ve made them pasta, people left quickly without bringing anything, but they’re keeping their spirits up, there’s a good atmosphere.”

By Friday, people’s homes were no longer in danger, with only a garage and a small hut damaged.

The Gard region fire service said on Friday morning that 13 firefighters were slightly injured.

As well as personnel on the ground, two planes have been dumping water since the early morning. On Friday, the air deployment had stretched to 12 firefighting planes and two helicopters.

Roads were closed to traffic entering the Bessèges area, while hundreds of firefighters remained on the scene, some drawn from neighbouring regions.

Like large swathes of the country, southeast France has suffered from drought this year, increasing the risk of fires.

During an unseasonable heatwave last month, about 600 hectareswere burned in a fire started by shelling on an army artillery training range near the Mediterranean port city Marseille.

Firefighters in that Bouches-du-Rhone region were called out to 35 outbreaks on Thursday, many of them close to inhabited areas.

Four houses were destroyed near southern city Arles and 250 firefighters were called out to a brushfire in Saint-Mitre-les-Remparts.

Although several other fires began in southern France on Thursday, most were put out before nightfall.

The fire service said thousands of hectares of heavily wooded land were under threat, as winds gusting at up to 50mph fanned the flames through the dried-out trees.

Wind is “the worst enemy” of firefighters, Agrinier said.

France’s national meteorological service put several neighbouring areas on red alert on Friday for fire risks and France’s environment ministry warned citizens in the area to beware fire risks.

Wildfires have also hit other countries in Europe this summer, including Greece and Portugal. Scientists say climate change brings more drought and higher temperatures that make it easy for fires to start and spread.