Madrid  - Thousands of people all over Spain staged silent rallies Thursday to protest the killing of a police officer by suspected activists of the militant Basque separatist group ETA.

Juan Manuel Pinuel, an officer with the paramilitary Civil Guard, was killed in a car bombing of the barracks where he was stationed in Legutiano in the Basque region early Wednesday. Four other officers were injured.

Deputy Prime Minister Maria Teresa Fernandez de la Vega, Interior Minister Alfredo Perez Rubalcaba and Defence Minister Carme Chacon participated in a rally in the Basque capital Vitoria after attending a funeral mass for Pinuel in the presence of Crown Prince Felipe.

Pinuel was ETA's sixth victim since Prime Minister Jose Luis Rodriguez Zapatero's attempt at a peace process with the group collapsed in December 2006. (dpa)