More than 100 wildfires stretched thousands of firefighters to the limit in northern Portugal on Wednesday, in the worst spate of fires in recent years.

Thousands of firefighters tackling deadly wildfires in central and northern Portugal had largely doused the flames in the Aveiro district, one of the worst-hit, as of Thursday morning, and were focusing on a dozen blazes still raging elsewhere.

More than 5,000 firefighters have been tackling the wildfires that Portuguese Prime Minister Luís Montenegro said are "raging across the country".