A bomb planted by the Basque separatist organisation ETA exploded Sunday in the norther Spanish city of Laredo, but there were no injuries, the dpa reported.
The report said that ETA had phoned in a warning ahead of the explosion, giving police time to evacuate a beach area where the bomb was planted. The device was planted near a beach promenade.
ETA told police it had planted a total of four bombs. The search was going on for the other devices, the radio said.