A bomb exploded at 8.45am this morning outside Guernica municipal court. Three other devices were detonated outside court houses in Berriozar (Navarra), Amurrio (Alava) and Ordizia (Guipúzcoa) last night and this morning.

The first went off at around 2.30am and damaged the main entrance of Ordizia municipal court. The second, which had been placed at the back of the court in Amurrio, exploded at 7.40am. The area has been cordonned by regional police and bomb squad experts are investigating the scene.

A warning call in the name of ETA was received by the Gara daily newspaper at 8.25am, around twenty minutes before the final bomb -which had been placed in a litter bin on the calle Adolfo Urioste- went off in Guernica.

Nobody was injured by any of the explosions, but PSN MP, José Antonio Navidad, explained that the blast on the calle Rekalde in Berriozar (photo) caused "serious damage" to office buildings and computer equipment, and that the resulting smoke had affected the school next door. Mr Navidad went on to explain that the bomb had been left on the sill of a barred window, and had frightened many people living nearby, who left their beds to come out into the street to find out what had happened.