Some 700 firefighters were battling Spain's first major forest fire of the year Saturday, which was raging out of control 48 hours after it began, forcing 1,500 people to flee.

In an update on Twitter, the regional emergency services said the fire in Villanueva de Viver, some 90 kilometres (55 miles) north of Valencia, was a "highly-complex blaze taking place in weather conditions similar to those of the summer".

"700 people have been mobilised for the operation (to fight the fire). It has affected 3,900 hectares and has a 35-kilometre perimeter," they said, indicating the number of people forced out of their homes on Friday, some 1,500, had not changed.

They said the huge blaze remained "very voracious" with the work to put it out "very complicated". Firefighters tweeted that they had deployed some 20 aerial units to help tackle the fire. "Clearly the fire has not stabilised because it is still burning with great ferocity given that the weather conditions are almost like summer," Ximo Puig, leader of the Valencia region told Spain's RTVE public television.

The fire began just after midday (1200 GMT) on Thursday. Firefighters said the blaze was more typical of summer than of late March. With the vegetation dried out by a lack of moisture in the atmosphere in recent months and large amounts of combustible biomass in the forests, conditions were "perfect" for such a blaze, Manolo Nicolas of the Castellon firefighters had told public radio on Friday.

 In 2022, which was a particularly bad year for wildfires in Europe, Spain was the worst-hit country with nearly 500 blazes that destroyed more than 300,000 hectares, according to figures from the European Forest Fire Information System (EFFIS).