Four bomb blasts struck two seaside resorts in northern Spain on Sunday.
The first two bombs hit a seafront promenade at Laredo, and the other two went off in sand dunes and a golf course in Noja, 30 miles away, police said.
One woman was slightly injured and a pregnant woman was treated for shock.
A fifth device exploded in a branch of Barclays Bank in Neguri, near Bilbao, at 5am on Sunday. The bank suffered minor damage and no-one was harmed.
The bombs were planted by Basque separatist militant group Eta, which has killed more than 820 people in its 40-year campaign for an independent Basque homeland. The attacks were seen by the Spanish government as an attempt to disrupt tourism during the holiday season.