Spanish police arrested four suspected members of ETA and seized nearly 200 kilogrammes (440 pounds) of explosives Tuesday, Deputy Prime Minister Alfredo Perez Rubalcaba said.

Police arrested the four suspects in night raids in Vizcaya, northern Spain, he said.

"We found an important quantity of explosives, around 200 kilogrammes, as well as various types of material to make bombs," Rubalcaba told a Madrid news conference.

It was the most important police operation against ETA since the group on January 10 declared a "permanent and general ceasefire" to be verified by the international community.

ETA's four-decade-long campaign of bombings and shootings for a homeland independent of Spain has claimed 829 lives.