At least seven people have died in flooding after heavy rain in the southern French department of Aude, the Interior Ministry said on Monday.

Flooding reached up to 7 metres high in the town of Trebes, the highest since 1891, according to local authorities and the government's flood warning service.

The equivalent of more than three months' rainfall fell in a few hours in the worst-affected areas, the ministry said.

In addition to the deaths, five people suffered serious injuries, with the ministry warning that the toll could rise.

All schools in the department were closed, and residents were warned to stay at home, the Aude prefecture said.

The villages of Cuxac d'Aude and Pezens, with a population of more than 5,000 people, were evacuated.

Later Monday morning, the prefecture warned riverside residents in the town of Carcassone to take refuge in the upper storeys of their houses.

Pedestrians and lorries were banned from crossing the town's bridges and motorists were advised to do so with caution.

Prime Minister Edouard Philippe said that 350 firefighters were at work and 350 more were on the way.

Seven civil rescue and military helicopters had also been mobilized but were unable to take off until the morning due to weather conditions, he added.

Sudden episodes of heavy rainfall are a recurring phenomenon along France's Mediterranean coast, especially in the autumn when warm air laden with moisture moves off the sea towards mountainous inland areas.

Last week, two people died when the car they were in was among five swept away by flooding near Saint-Tropez on the French Riviera.

However, the current episode in Aude is much more severe than usual, according to the national flood warning service Vigicrue, which said the flooding at Trebes was close to the record high of 1891.