Spanish Prime Minister Jose Luis Rodriguez Zapatero said the Basque separatist group ETA had been dealt a "decisive" blow with the arrest of its suspected military chief Monday.
ETA "has not lost its capacity to to attack all citizens. It has not lost its capacity to cause harm," he said in a statement read on television.
"But with this arrest it has suffered a hard blow to its organisation and its capacity," he said. "Today, ETA is weaker and Spanish democracy is stronger."
French police arrested Miguel De Garikoitz Aspiazu Rubina, who went by the alias "Txeroki", and an alleged female accomplice overnight in Cauterets, a spa and ski resort in the Pyrenees near the border with Spain's autonomous Basque region.
"Someone who for some time has led the operations of the terrorist group ETA has fallen, someone who was directly responsible for the recent killings committed by ETA," he said.
"Without doubt, it is a major a step forward, a decisive action."
The arrest fulfilled a promise by the government to capture those responsible for the killings of two members of Spain's Civil Guard police force in southwest France last December, Zapatero added.
That attack had been "one of the bloodiest and most despicable" by ETA, he said, adding that "his (Txeroki's) participation appears to be clear."
ETA, which has killed 824 people in its 40-year campaign for an independent Basque homeland, had claimed responsibility for the December 1 attack in a statement issued two weeks afterwards.
Txeroki's arrest came just six months after that of the militant separatist group's presumed leader, 49-year-old Javier Lopez Pena.
Zapatero thanked the French President Nicolas Sarkozy, Interior Minister Michele Alliot-Marie and the French police who "once again showed their will to work together (with Spain) in this tireless struggle."
France, once a safe haven for Basque militants, has arrested a number of ETA suspects since the group called off a 15-month-old ceasefire in June 2007, shattering hopes of a peace settlement.
