France mobilised 1,500 firefighters Wednesday to deal with wildfires in countryside north of Marseille that have gutted buildings and forced more than 1,000 people to flee their homes.

Whipped up by strong winds, the blaze took hold around 3:30 pm (1330 GMT) and has spread over 2,260 hectares (5,600 acres) of scrubland, grass and some wooded areas, according to firefighters.

"We haven't seen a situation like this for a very long time," the fire service said, first calling the wildfires "out of control" but later describing more favourable conditions in the night.

Homes were destroyed in the town of Vitrolles, some 30 kilometres (20 miles) north of Marseille, with more than 1,000 people forced to seek shelter in local sports centres.

Dramatic images showed a helicopter battling to douse a blazing hillside with water just metres from a motorway close to Vitrolles, while one person was seriously injured in nearby Rognac.

The blaze -- which comes after low rainfall in winter and spring left southeast France extremely dry -- sent a huge pall of smoke into the sky over the port city of Marseille.

"The fire seems to be less intense than before but is not yet under control," Marseille mayor Jean-Claude Gaudin said in a tweet.

Further west in Herault, four firefighters were injured battling another blaze when their vehicle was surrounded by the flames.

Hundreds of extra firefighters have been drafted in from elsewhere in France to tackle the blaze.

Road and air transport were badly affected by the fire on Wednesday evening, with two motorways closed and some flights cancelled at Marseille airport.