French police have arrested the second most senior member of the Basque separatist group ETA and two other suspected militants, Spanish Interior Minister Jose Antonio Alonso said on Monday. Police arrested Harriet Aguirre, suspected lieutenant to ETA leader Garikoitz Aspiazu, or 'Txeroki', and another leading member Idoia Mendizabal, Alonso told a news conference. The third suspect had not been identified, Reuters reported. ETA, classed as a terrorist group by Spain, the European Union and the United States, has killed about 850 people in its four-decade campaign for an independent state carved out of northern Spain and southwest France.