Backed by water-dropping aircraft, firefighters were trying to bring under control some 50 blazes nationwide that have forced many residents to evacuate their homes.

The most devastating blaze was burning through the wooded hills of Monchique in the southern Algarve region, where 400 firefighters have been deployed in a difficult-to-access rocky area.

Vitor Vaz Pinto, head of emergency services there, said that after dying down, the fire had re-started on Wednesday evening “in an explosive manner.”

“It’s hell,” a local resident said on Portuguese television.

“I don’t know if someone set fire to the area, or if the wind fanned the flames.”

Up north, meanwhile, a large-scale blaze was raging in the Douro International Natural Park, near Freixo de Espada a Cinta on the border with Spain.

“We have had to evacuate a retirement home, the flames came very close,” said Joao Possacos, mayor of the affected village of Bruco.

Across the border in Spain to the northwest, firefighters and water-dropping aircraft continued to battle four blazes, forcing the evacuation of several houses.

Other fires continued in the north and southwest of Spain.

But Agriculture Minister Isabel Garcia Tejerina has played down the scale of the fires this year.

According to her ministry, wildfires destroyed almost 40,000 hectares (100,000 acres) of land between January and August — an area close to the size of Barbados.

But this is still far less than the average for the period, which since 2006 has been around 78,000 hectares.

Many of the fires are suspected to be the work of arsonists.

On Thursday, a man was arrested in a natural park in the southern Spanish region of Andalusia, suspected of having set paper and plastic bags on fire to try to spark a blaze near the small town of Almaden de la Plata.

“He is a resident (in the area) and has confessed,” a spokesman for police in Andalusia told AFP.