LISBON, Portugal -- More than 1,000 firefighters on Monday were battling a major wildfire amid scorching temperatures in Portugal, where forest blazes wreak destruction every summer.
About 90 per cent of the fire area in the Castelo Branco district, 200 kilometres (about 125 miles) northeast of the capital Lisbon, was brought under control during cooler overnight temperatures, according to local Civil Protection Agency commander Pedro Nunes.
But authorities said they expected heat and winds to increase again in the afternoon, and warned that forests are tinder-dry after weeks with little rain.
Nunes told reporters that the fire, in its third day, has injured 31 people.
The Portuguese Civil Protection Agency said 321 vehicles and eight water-dumping aircraft were deployed to tackle the blaze, which has raced through thick woodlands.
Police said they were investigating what caused the fire amid suspicions it may have been started deliberately.
Temperatures were forecast to reach almost 40 C (104 F) Monday -- prolonging a spell of blistering weather that is due to hit northern Europe late this week.
Recent weeks have also seen major wildfires in Spain, Greece and Germany. European Union authorities have warned that wildfires are "a growing menace" across the continent.
In May, forest fires also plagued Mexico and Russia.
Huge wildfires have long been a summer fixture in Portugal. The country's deadliest fire season came in 2017, when at least 106 people were killed.
The average annual area charred by wildfires in Portugal between 2010 and 2016 was just over 100,000 hectares (247,000 acres). That was more than in Spain, France, Italy or Greece -- countries which are significantly bigger than Portugal.
Almost 11,500 firefighters are on standby this year, most of them volunteers. Volunteers are not uncommon in fire brigades in Europe, especially in Germany where more than 90% are volunteers.
Experts and authorities have identified several factors that make Portugal so particularly vulnerable to forest blazes. Addressing some of them is a long-term challenge.
The population of the Portuguese countryside has thinned as people have moved to cities in search of a better life. That means woodland has become neglected, especially as many of those left behind are elderly, and the forest debris is fuel for wildfires.
Large areas of central and northern Portugal are covered in dense, unbroken stretches of forest on hilly terrain. A lot of forest is pine and eucalyptus trees, both of which burn fiercely.
Environmentalists have urged the government to limit the area of eucalyptus, which burns like a torch. But it is a very valuable crop for Portugal's important paper pulp industry, which last year posted sales worth 2.7 billion euros ($3 billion). The government says it is introducing restrictions gradually.
Experts say Portugal needs to develop a diversified patchwork of different tree species, some of them more fire-resistant and offering damper, shaded.
Climate change has become another challenge, bringing hotter, drier and longer summers. The peak fire season used to run from July 1 to Sept. 30. Now, it starts in June and ends in October.
After the 2017 deaths, the government introduced a raft of measures. They included using goats and bulldozers to clear woodland 10 metres (33 feet) either side of country roads. Property owners also have to clear a 50-meter (164-feet) radius around an isolated house, and 100 metres (328 feet) around a hamlet.
Emergency shelters and evacuation routes have been established at villages and hamlets. Their church bells aim to toll when a wildfire is approaching.
With 98% of blazes caused by human hand, either by accident or on purpose, officials have also been teaching people how to safely burn stubble and forest waste. Police, army and forest service patrols are also increased during the summer.