A fire broke out Wednesday on the roof of the airport in Alicante, a city on the eastern Mediterranean coast which is a tourism hotspot, forcing its closure to air traffic.
"The fire is under control but it has not been extinguished. Firefighters are continuing to work," a spokesman for Spanish airport operator Aena told AFP, adding the airport will remain closed to air traffic until noon on Thursday.
Ten flights which were due to land at Alicante were cancelled, as were 12 which were supposed to depart from the airport, he said.
Another four flights which were due to land at Alicante were diverted to other Spanish airports.
The flames were visible from inside the terminal, according to an AFP photographer at the scene.
Passengers and workers stood outside as dense smoke rose from the terminal building.
No one was injured and the authorities are still not sure what caused the fire.
The airport serves the eastern region of Valencia, which is home to several popular resorts such as Benidorm. It handled just under 14 million passengers last year, making it Spain's fifth busiest airport.
Aena recommended in a tweet that passengers contact their airline before heading to Alicante airport to see what the status of their flight was.
"We are coordinating with airlines. Consult your company to know if your flight is cancelled or will operate from an alternative airport," it said.