"Fire tourists" have been urged to keep away from blazes raging in eastern Spain after wildfire season arrived earlier than expected.
Officials have said onlookers have been putting themselves at risk and disrupting efforts to extinguish flames.
More than 500 firefighters, supported by 20 planes and helicopters, were battling a fire four days after it broke out near the village of Villanueva de Viver in the Valencia region, emergency services said.
Police had spotted 14 cyclists near the scene trying to get a closer look, Valencia's regional head of interior affairs Gabrielo Bravo told reporters.
"We ask once again and above all tourists not to engage in fire tourism, not to approach the perimeter area," she said.
Spain's first major wildfire of the year has destroyed more than 4,000 hectares (9,900 acres) of forest and forced 1,700 villagers to leave their homes in the Valencia and Aragon regions in eastern Spain, officials said.
People have recalled leaving their animals behind as they had to flee their homes.
Residents said the fire could have a devastating impact on the local economy which depended on tourism.
"The people here live from cycling, hiking, and the few bars," said Jorge Grausell, 72.
"You see this and it is a disaster for anyone who likes nature."
Ximo Puig, the president of the Valencia region, told reporters on Friday that the wildfire was "very early in the spring, very voracious from the beginning".
He added that the effects of climate change "are undeniable, so the perspective of firefighting must be considered on an annual basis".
An unusually dry winter across parts of southern Europe has raised fears there could be a repeat of last year's devastating wildfires.
Last year, about 785,000 hectares were destroyed in Europe, more than double the annual average for the past 16 years, based on European Commission (EC) statistics.
In Spain, 493 fires destroyed a record 307,000 hectares of land last year, according to the Commission's European Forest Fire Information System.