Hundreds of civilian and military firefighters are tackling a wildfire in south-west Spain that has burned across at least 7,500 hectares (18,500 acres) of land and forced the evacuation of more than 500 people since it began on Wednesday evening. Efforts to fight the “very large and difficult” fire in the Las Hurdes and Sierra de Gata areas of northern Extremadura are being hindered by strong winds, according to the regional government, which says the blaze was started deliberately. People in three villages – Cadalso, Descargamaría and Robledillo de Gata – have been evacuated and three main roads closed. The regional government said more than 500 firefighters, including members of the military emergencies unit, had been deployed and were using 10 earthmovers, six planes, eight helicopters, and 23 road vehicles to try to bring the fire under control. “The problem isn’t human and material resources,” Extremadura’s president, Guillermo Fernández Vara, said during a visit to the affected area on Friday. “The problem is the wind and gusts of up to 60km per hour, which are making it incredibly difficult to control the fire.” Fernández Vara said whoever had started the fire had known what they were doing, adding: “The pine trees are like petrol cans and the pine cones are like flame-throwers.” Spain’s prime minister cancelled a campaign trip to the region in advance of next week’s local and regional elections. Pedro Sánchez said he was following the situation closely and offered those affected his full support. Begoña García, the head of Extremadura’s agriculture department, asked people in the area to let police know if they had seen anything suspicious, adding that residents “know that this was done on purpose”. Local emergency services also asked people to keep out of the affected areas so as not to clog up evacuation routes. Marcos Hernández, who lives in Pinofranqueado, the municipality where the fire began, told the Efe news agency that people in the area felt “very angry” and powerless as the blaze continued. Fires in 2003 devoured more than 8,000 hectares of land in Las Hurdes and blazes in the same area burned through more than 5,000 hectares last July. According to the European Forest Fire Information System, more than 315,000 hectares of land in Spain was engulfed by wildfires last year. The Spanish government last week approved a €2.2bn (£1.9bn) plan to help farmers and consumers cope with an enduring drought that has been exacerbated by the hottest and driest April on record. The environment minister, Teresa Ribera, said the effects of the climate emergency were becoming increasingly evident. “Spain is a country that is used to periods of drought but there’s no doubt that, as a consequence of the climate change we’re experiencing, we’re seeing far more frequent and intense events and phenomena,” she said.