A bomb exploded on Saturday at a business in Spain's Basque country, causing no injuries, after a warning call in the name of Basque separatist guerrilla group ETA, police said.
The telephoned warning to a Basque newspaper and the regional highway authority gave police time to evacuate the business, that sells eels, and cordon off the area.
As a precaution, police temporarily closed the busy N1 motorway that runs close to the business at Irura, near the Basque coastal resort of San Sebastian.
A police spokesman said no one was injured in the blast. He had no information on damage, but news reports said it was extensive.
Employees of the company earlier spotted a suspicious rucksack at the entrance to the building, the police spokesman said.
ETA, considered a terrorist organisation by the European Union and the United States, has killed nearly 850 people since 1968 in a bombing and shooting campaign for an independent Basque state in northern Spain and southwestern France.
It often attacks or threatens businesses in the Basque country in a bid to force them to pay a "revolutionary tax" with which it funds itself.
No one has been killed in an ETA attack for more than two years but the group still regularly carries out small-scale bombings.
Police said ETA was probably to blame for a December 11 blast outside a Basque post office that caused substantial damage but no injuries.
The Spanish government said in May it would talk to ETA if the group laid down its arms, but a Basque newspaper recently quoted ETA's internal bulletin as saying the group would not declare a ceasefire until the Spanish and French governments made concessions.
