A double bombing in northern Spain has destroyed 11 trucks in the early morning hours of the country's national day.

No one was hurt by the explosions, which were caused by two one-kilogram bombs placed under the trucks in the northern town of Irun, located on Spain's border with France.

Local police said no one has claimed responsibility for the attack but they suspect it was set by the Basque separatist group ETA, which has launched attacks on October 12 in previous years.

Last week Spanish and French police rounded up at least 29 suspected ETA members for questioning. Nine were freed Sunday, while the others remain in custody.

ETA claims responsibility for the deaths of more than 800 people since it began a series of guerrilla attacks in 1968. ETA members want an independent Basque state in northern Spain and southern France.

The United States and the European Union say ETA is a terrorist organization.