A major wildfire in eastern Spain that has destroyed vast swathes of land gathered pace overnight after flaring up again despite heavy rainfall, as another started Friday inside a nearby natural park, officials said.

So far this year, Spain has suffered nearly 400 wildfires following punishing heatwaves and long dry spells that have devastated more than 283,000 hectares of land, more than three times the total area destroyed in 2021.

Over the past week, hundreds of firefighters have been battling two major wildfires raging out of control in the Valencia region, with a bout of heavy rainfall offered some respite, almost totally extinguishing the flames.

Although it put an end to the Vall d'Ebo fire near Benidorm, the Bejis blaze some 70 kilometres (45 miles) northwest of Valencia city, flared up again and burning its way towards the Sierra Calderona natural park.

It has already destroyed 19,000 hectares (50,000 acres) of land.

"The fire advanced slowly during the night except in... areas to the southeast where it has raged more aggressively," the emergency services tweeted, indicating 35 aerial firefighting teams were trying to contain the blaze.

"There are flames all along the perimeter," it added.

The UME military firefighting said on Twitter it had been an "intense night" in Bejis, posting images of huge flames.

"It's a very big fire with a perimeter stretching more than 120 kilometres so we've using all the means we have to contain the fire," Mariano Hernandez, one of the provincial fire chiefs, told public television.

Early on Friday another blaze began at Olocau inside the Sierra Calderona park, some 40 kilometres southeast of Bejis, the emergency services said.

It added that local residents had been "confined to their homes as a preventative measure".

The Vall d'Ebo fire began on Saturday and the Bejis blaze two days later, forcing some 3,000 people to be evacuated in total.

So far this year, Spain has been hit by 391 wildfires, the latest figures from the European Forest Fire Information System show.

The fires have destroyed more than three times the area consumed by wildfires in the whole of 2021, which totalled over 84,000 hectares, the figures show.