Spain has officially asked for assistance from its European neighbours to fight forest fires that have been raging through the country's northwest.

A volunteer firefighter died from severe burns and several people were hospitalised as the state weather agency warned that almost all of the country was at extreme or very high risk of fire.

Spain is battling a series of devastating wildfires that have killed two people and destroyed thousands of hectares of forest and scrubland. There are currently 14 major active fires, Minister for Ecological Transition Sara Aagesen told radio station Cadena Ser on Wednesday.