Bombs exploded near magistrates courts in four Spanish towns early today.
The explosions damaged buildings but no one was injured, officials said. Police said they suspected the armed Basque separatist group Eta was to blame
Basque police said a caller claiming to represent Eta warned the newspaper Garashortly before one bomb exploded in a rubbish bin in the Basque town of Guernica. Journalists said the bomb twisted a railing outside a school near the court.
There were also explosions at Ordizia and Amurrio in the Basque country; the fourth blast, caused by a home-made bomb placed by the window of a court, was at Berriozar in Navarre, a region adjoining the Basque country, police said.
Eta has killed nearly 850 people since 1968 in its campaign for an independent Basque state carved out of northern Spain and southwestern France. It is classed as a terrorist organisation by Spain, the European Union and the United States.
Police in both countries have arrested dozens of Eta suspects in the last year, including many senior leaders. The organisation has carried out about 20 minor attacks this year but has not killed anyone since May 2003.
Spain's Socialist government recently offered to talk to Eta if the group laid down its arms, but Eta has continued to carry out sporadic bombings.