Portugal's prime minister is warning against complacency in the fight against wildfires after huge blazes in 2017 that killed more than 100 people were followed by two years of much smaller charred areas and no deaths.

Antonio Costa said at a ceremony Monday honoring some of the 2017 fatalities that blazes which traditionally race through Portuguese forests every summer won't be stopped without improving forest management and ensuring that local people don't abandon rural areas.

Costa says record firefighting assets deployed by the government aren't a long-term solution.

Wildfires blackened more than 500,000 hectares (1.23 million acres) in 2017, compared with a 10-year annual average of about 140,000 hectares.

Amid unprecedented precautions, burned forest dropped to 44,000 hectares in 2018 and just over 7,000 hectares so far this year.