Seven bombs went off in different Spanish cities today in the space of half an hour, slightly injuring five people.
Anonymous callers claiming to speak for the underground Basque separatist group ETA had told a Basque newspaper to expect the explosions.
The interior ministry said three people including two police officers were injured in the central city of Ciudad Real and two more in northern Santillana del Mar.
Minor explosions also occurred in northern Leon, Valladolid and Avila and in southern Alicante and Malaga soon after 12.30pm Irish time.
The explosions come three days after ETA detonated five bombs simultaneously at petrol stations along major highways in and around Madrid, slightly wounding two police officers.
A number of people reported hearing difficulties following the blasts. However, no serious injuries were reported.
The warning from ETA was published on the Internet on the website of the Basque newspaper, Gara. ETA reportedly made two separate calls to the newspaper warning of the attacks.
Today is a public holiday in Spain celebrating the 1978 constitution, marking the return to democracy after the four-decade dictatorship of General Francisco Franco.
Police had warned of a possible terrorist attack coinciding with the holiday.
