In an attack seen as targeting the country's key tourism sector, four bombs planted by the Basque separatist organisation ETA exploded Sunday in northern Spain, resulting in one injury, officials said, dpa reported.
The banned underground group gave advance warning of the explosive devices, providing police a chance to evacuate the areas, officials said.
Contrary to earlier reports, officials later said one person was injured by a stone which a blast had sent flying. Also, a pregnant woman had to be taken to hospital in suffering a panic attack.
After the telephone warning about one and one-half hours before the first blast, police evacuated the beach areas and the golf course. Police used loudspeakers to urge people not to leave their homes and hotels.
The four bombs exploded over a span of three hours on two beaches and a golf course near the resort towns of Laredo and Noja, near the city of Santander and only a few kilometres from the country's Basque region. The blasts caused only minor property damage.
Investigators were convinced that ETA was now launching a new offensive targeting vacation resort areas, timed precisely during the busy season in Spain's vital tourism industry.
Over the past 30 years, ETA has set off more than 100 bombs in Spanish vacation areas. But the attacks did nothing to stop the steadily rising number of tourists over the years.
In May the ETA threatened a new wave of terrorism after the group's suspected highest-ranking leader, Francisco Javier Lopez Pena, was capture in France.
In recent weeks the group had also carried out several bomb attacks in the Basque region, one targeting a radio broadcasting facility and the other a newspaper office. There were no injuries in those blasts.
The group has been fighting the past 40 years for an independent Basque state, with its violence during this period claiming nearly 850 lives.