MADRID British police arrested a suspected member of Basque separatist group ETA in the northern English city of Liverpool on Friday, Spain's Interior Ministry said in a statement.
It identified the man as 46-year-old Raul Sanchez Fuentes Villota and said he was linked to a series of murders and had been on the run since 1995. He was living in Britain using false documentation, it said.
Fuentes Villota was a member of regional branches of ETA that carried out several murders and planted a car bomb, among other crimes in the early 1990s, the Ministry said.
Merseyside Police in Liverpool said they were working with the Spanish Embassy on Fuentes Villota's extradition. A spokeswoman added that he would appear in court in London "as soon as possible".
Euskadi Ta Askatasuna (ETA), meaning Basque Homeland and Freedom in Basque, is an independence movement dating back to the late 1950s. The group said a year ago that it would give up its armed struggle, which had claimed more than 800 lives.
ETA had been weakened by the arrests of most of its leaders and by waning support in the northern Basque Country region. In October the suspected head of its military wing was arrested in France.
But Spain's government has declined to negotiate a definitive end to the conflict, insisting that ETA first formally disband and hand over weapons.
(Reporting by Clare Kane in Madrid and Peter Schwartzstein in London; Editing by Mark Heinrich)