A light helicopter that was taking part in firefighting efforts in northern Portugal crashed and exploded on Sunday, killing its pilot and further raising the death toll from the country's deadliest summer of wildfires, officials said.

"The helicopter hit high-tension wires and crashed. The aircraft caught fire after hitting the ground, causing the death of the pilot, who was the only person onboard," Civil Protection Commander Rui Esteves told a briefing.

The incident occurred in the Castro Daire area, 320 km (200 miles) northeast of Lisbon.

Under pressure to limit the damage since a single fire killed 64 people in June, the government last week declared a state of public calamity in various parts of the country which has borne the brunt of a heatwave across much of southern Europe.

Since that tragedy, emergency services have made far greater efforts to evacuate villages and shut roads early in affected areas.