A Spanish soldier was shot and wounded in San Sebastian last night.
No group has claimed responsibility for the shooting, which happened near an army barracks at around 10pm local time, but politicians said they feared Basque separatists Eta were responsible.
The group was blamed for a car bomb last week in the nearby Basque city of Bilbao that injured the bodyguard of a local politician.
In addition to the car bombing, Eta has been blamed for an armed raid on a French factory last week in which 2,000 litres of a chemical used in explosives was stolen.
All three incidents have come within days of the arrest of top leaders from radical party Batasuna, banned because of links to Eta.
The separatists have killed more than 800 people in four decades of armed struggle.
It has carried out several attempted attacks since calling off a ceasefire in June, but no one has died since two people were killed by a car bomb at Madrid airport in December.