LEIRIA, Portugal - Five years after Portugal's deadliest wildfire, which claimed 63 lives, a court on Tuesday acquitted 11 people accused of negligent homicide over the tragedy.

The fires broke out in the central Leiria region during a heatwave in June 2017 and burnt for five days, destroying 240 sq km of hillsides covered with pine and eucalyptus trees.

A senior firefighter and several local officials were in the dock, alongside employees of a power company and a firm responsible for maintaining a road in the Pedrogao Grande district where around 40 of the victims died.

Another 44 people were injured.

While the court in Leiria found failings in the prevention and control of the forest fire, presiding judge Maria Clara Santos said the scale of the disaster was caused by a natural phenomenon of "unique and totally unpredictable" force.

Many of the victims died trapped in their cars while trying to escape the flames, which were fanned by violent winds.

The defendants had been accused of failing to prevent or combat the fire that swept through the rural area 200km north of Lisbon.

But the court said in a statement shared after the hearing that "it had not been proven that the deaths and injuries were the result, by action or omission, of the conduct of any of the defendants".

Several of the victims' relatives were in the crowded courtroom in Leiria city for Tuesday's hearing.

'Calm the families'

Less than six months after the Pedrogao Grande disaster, a new series of deadly wildfires broke out in the centre and north of the country, killing another 45 people.

Augusto Arnaut, who was commander of the Pedrogao Grande fire brigade at the time of the disaster in June, is accused of not taking action early enough to control the blaze before it raged out of control.

But the Portuguese Firefighters League issued a statement on Monday saying it believed Arnaut was innocent and had done all he could.

And on Tuesday, around 100 uniformed firefighters formed a silent guard of honour for Arnaut outside the court.

Three executives from road maintenance company Ascendi could face prison too.

Prosecutors said they had acted irresponsibly by not ensuring the clearing of vegetation from verges through which many victims sought to escape the flames.

An employee of the electricity distribution network could also face a stiff sentence because the fire was sparked by a discharge from a power cable above tinderbox scrub.

Forests 'neglected'

Several local officials from Pedrogao Grande, Castanheira de Pera and Figueiro dos Vinhos - the three worst-affected districts - are charged with failing to maintain the forests along the roads and under power lines.

Prime Minister Antonio Costa accepted that the state bore some responsibility in the fires of June and October 2017, which killed 117 people.

The victims' relatives received compensation worth a total of €31 million (S$43 million).

The Socialist leader promised to overhaul Portugal's firefighting capacity, burying power lines and turning the largely volunteer fire brigades into professional forces.

But forestry engineer Paulo Pimenta de Castro told AFP the situation now is "worse than in 2017".

"Many forested areas are just left neglected (and) there has been no root and branch reform to firefighting, just superficial changes," he said.

He gave the example of a wildfire just last month that destroyed another 240 sq km, this time in the protected Serra da Estrela Natural Park, also in central Portugal. AFP