French police have arrested a man suspected of being a leader of the armed Basque separatist group ETA and responsible for a number of killings in the 1980s.
The man, identified as Felix Ignacio Esparza Luri, was detained close to Dax in southwest France. French police said he had been under surveillance for some time and a broader operation was still going on.
The security source said the arrest was a major coup for French and Spanish police, who have increased their co-operation in recent years as part of a crackdown on ETA.
"He was in charge of the terrorist group's logistical organisation and was responsible for explosives, vehicles and border crossings," a source said of Esparza Luri.
ETA has killed some 840 people in its decades-long fight for an independent Basque homeland carved out of northern Spain and southwest France.
Spain's incoming Socialist government dismissed an offer from the guerrillas to open peace talks, saying the group must first renounce violence.