Spain went on maximum alert on Friday as ETA marked its 50th anniversary after two bombings this week blamed on the Basque separatist group, including an attack that killed two police officers.
Prime Minister Jose Luis Rodriguez Zapatero and other political leaders paid their respects to the officers slain in yesterday's attack in Majorca as they attended a funeral service in the southern island, pinning the blame on ETA.
The approach to the anniversary has seen an upsurge in violence, with a massive car bomb exploding outside a police barracks in Burgos in northern Spain on Wednesday which lightly injured 64 people.
Police also found a second bomb in Majorca on Thursday under another police car at a separate nearby barracks and carried out a controlled explosion.
Zapatero blamed the attacks "on the terrorist group ETA" and vowed to bring all members of the outfit to justice.
"I want to assure citizens that the government has instructed security forces to be on maximum alert, that they redouble their dedication, that they boost even more their efforts and also that they protect themselves from these vile assassins," he said on Thursday night.
"They have no chance to hide, they can't flee, they can't escape justice, they will be detained, they will be sentenced, they will spend their lives in jail," he added.