A bomb has exploded outside a court in Spain's north-eastern Basque region, after a warning from ETA, the armed separatist group, Spanish media report.
The small blast went off at 0115 (0015 BST) in the town of Tolosa and no injuries were reported.
The device was reportedly left in a rucksack on the steps of the court, reported BBC.
The attacks come at a time of increased turbulence in Basque politics after Spanish courts banned two Basque parties over their links to Eta.
Spanish public television station TVE said a man claiming to represent ETA called the Basque traffic department to warn of an imminent blast about half an hour before the explosion.
Eta's four-decade campaign to set up an independent state straddling northern Spain and south-western France has led to more than 800 deaths.
The group resumed its campaign of violence in December 2006, following the failure of secret dialogue with Spain's Socialist government.
Last month, eight people were arrested after a series of car bombs in northern Spain which killed a Spanish army officer and injured several others.