A woman suspected of being a military leader in the armed Basque separatist group Eta has been arrested in France, the Spanish interior ministry says.
Izaskun Lesaka and another Eta suspect were arrested by French police in the town of Macon, a statement said.
It described Ms Lesaka as one of the "three most important figures" in Eta, and said both suspects had been armed.
Eta announced a "definitive end" to its armed campaign in October 2011, but Spain has demanded that it disband.
In May the Spanish government rejected a request for talks from Eta, whose 45-year campaign for independence has claimed over 800 lives.
The group is considered a terrorist organisation by Spain, the EU and the US.
The Spanish interior ministry named the other man detained as Joseba Iturbide Ochoteco, and says the arrests bring to 24 the number of Eta suspects arrested since January.
Ms Lesaka' arrest is crucial as she controlled the organisation's reserves of arms and explosives, the ministry said, adding that she was one of three masked figures who read out Eta's ceasefire announcement last year.
She is thought to have been on the run for at least seven years.
Eta has been weakened in recent years by a string of arrests of its key members, mostly in Spain and France.
Earlier this month, Basque nationalist parties won regional elections, a result expected to fuel calls for independence.
One of the groups that did well, the Euskal Herria Bildu coalition, represents the political ambitions of those who in the past supported Eta.
However, Bildu has publicly condemned the use of violence for political ends.