Spanish police on Tuesday arrested four suspected members of the armed Basque separatist group ETA they believe may have been behind several attacks in recent years, the interior minister said.
Alfredo Perez Rubalcaba described the arrests as being of "enormous importance" and said police had also seized some 200 kilograms of explosives and bomb-making material in the raids in the northern Basque province of Vizcaya.
Spanish newspaper El Pais and other media said the detainees were wanted for several attacks including the killing of an anti-terrorism officer in 2009 and the car-bombing of a Civil Guard barracks in the northern city of Burgos the same year.
Rubalcaba, however, said only that police hoped the arrests would help clear up several unresolved attacks in Vizcaya and surrounding regions but declined to give any details of the detainees' suspected crimes.
ETA announced a permanent cease-fire in January but the government insists it must disband and lay down arms.
Rubalcaba said the operation showed that Spain's anti-terrorist policy "had not changed one iota."
"It hasn't changed for the simple reason that ETA has not abandoned violence definitively. It hasn't said goodbye to arms forever and until that happens, the police and Civil Guard will continue working, arresting them one by one until this finishes for good," he said.
The group has killed more than 825 people since the late 1960s in a campaign for an independent Basque state straddling northern Spain and southwest France. It is considered a terrorist organization by Spain, the European Union and the U.S, has been weakened by arrests of its members and by dwindling support.