The blaze in north Portugal's Viana do Castelo district was spreading in two directions and was difficult to tackle because of the strong winds, civil protection chief Marco Domingues said.

One firefighter has been injured.

Authorities have put much of northern and southern Portugal on the highest alert for wildfires because of high temperatures and strong winds.

The country faces annual summer wildfires, which experts say are becoming more frequent and intense around the world because of rising global temperatures.