A car bomb blew up in a car park at Santander airport in northern Spain today after a warning by the armed Basque separatist group ETA, police said.
There were no immediate reports of casualties. Local media said a plume of smoke was rising from the airport parking lot, which lies close to the coast.
A Basque newspaper had received a call minutes earlier in the name of ETA warning of the explosion, officials said.
Santander is a busy port and seaside resort packed with holidaymakers during the summer. The explosion follows a week of renewed activity by ETA following a lull in attacks.
A bomb exploded outside a Spanish courthouse, injuring a man, after a warning from ETA on Friday and two home-made bombs blew up in the troubled Basque country the same day.
Two bombs exploded at Spanish seaside resorts on Tuesday, injuring 13 people, in what authorities called the start of ETA's traditional summer bombing campaign aimed at undermining the crucial tourist sector.
ETA, branded a terrorist organisation by the United States and the European Union, has killed more than 800 people in a three-decade campaign for an independent Basque state in northern Spain and southwestern France.