Villagers, as well as authorities in Macao and Vila de Rei, areas in the heart of the fire zone, said there were not enough firefighters and resources to combat the flames.
Sheep farmer Joaquim Ribeiro told Reuters there were no firefighters when the blaze arrived at his village in Macao, forcing him to transfer his animals elsewhere. "It was pandemonium."
Another sheep farmer, Fernando Cardoso, said he rushed to a nearby fire station as the flames approached his village but the firefighters told him they could not help until given the green light.
"The fire appeared out of nowhere," he said. "When we got here, there were flames everywhere, no place to turn, no firefighters, there was no one."
Local authorities have also pointed the finger at Portugal's Socialist government, led by Prime Minister Antonio Costa.
Speaking to Lusa news agency, the deputy mayor of Vila de Rei, Paulo Cesar, accused the government of not being able to prevent wildfires.
"The municipality is fed up with these successive fires linked to criminal activity and is fed up of seeing the state fail again," he said.
Asked by reporters about the complaints, Costa said the mayors were "primarily responsible" for protecting their own municipalities from wildfires through "proper management of their territory".
Internal Administration Minister Eduardo Cabrita said police had opened an investigation into the fires. Portugal’s judiciary police have collected evidence and artifacts that could be related to the fires' origin, an official told Lusa news agency.
In a statement, police said a 55-year-old man was detained on suspicion of starting a blaze in the Portuguese district of Castelo Branco. But a police source, quoted by Portuguese newspaper Observador, said the detention was not related to the fires in question.
The police did not reply to a Reuters request for comment.
Civil Protection said 1,079 firefighters were on the ground, backed up by 347 firefighting vehicles.
Spain said late on Monday that it was sending two aircraft to help tackle the fires in Portugal.
