Thousands of firefighters backed by the military and water-bombing aircraft on Monday battled dozens of wildfires across Spain and Portugal, as the death toll increased to six since the outbreaks began.

The Iberian peninsula has been particularly affected by forest fires fuelled by a succession of heatwaves and droughts blamed on climate change that have hit the southern Mediterranean.

Two firefighters were killed on Sunday – one in each country, both in road accidents – taking the death toll to two in Portugal and four in Spain.

The fires, now in their second week, were concentrated in Galicia, Castile and Leon, and Extremadura regions.

In the Ourense province of Galicia, northwestern Spain, signs of the fires were everywhere, from ashen forests and blackened soil to destroyed homes, with thick smoke forcing people to wear facemasks.

Firefighters in protective clothing, armed with fire beaters, battled to put out fires, as locals in just shorts and T-shirts used water from hoses and buckets to try to stop the spread.

"In my 75 years, I truly mean it, I have never experienced anything like this before," a woman in the town of O Barco de Valdeorras said.

Another resident dousing his home with water from a hosepipe described the wildfire that ripped through his area as "like a bomb".

"It came from below and it was like a hurricane," he said. "The good thing was that in two minutes it headed up and it didn't stay here long. If not, our house would have been burnt, it would not have survived."

Elsewhere in the southern Mediterranean, the authorities in Turkey said two major fires had been brought under control, while rain and falling temperatures have helped firefighters extinguish dozens of blazes in the Balkans.

Spain is being helped with firefighting aircraft from France, Italy, Slovakia and the Netherlands, while Portugal is receiving air support from Sweden and Morocco. (AFP)