Tunisian protesters burned down a regional national security headquarters near the Algerian border, prompting authorities to send in troops after police retreated, witnesses said, as unrest over prices and taxes continued nationwide.
Over 600 protesters were arrested overnight and the army was deployed in several cities to help quell violent protests in Tunisia seven years after the overthrow of autocrat Zine El-Abidine Ben Ali in the first of the Arab Spring revolts.
In Thala, near the Algerian border, soldiers were deployed after crowds torched the region's national security building, forcing police to retreat from the town, witnesses told Reuters.
Tunisia's unity government - which includes Islamists, secular parties and independents - has portrayed the unrest as driven by criminal elements, and Prime Minister Youssef Chahed has accused the opposition of fuelling dissent.
Rejecting that accusation, Tunisia's main opposition bloc, the Popular Front, called for a major protest in Tunis on Sunday to coincide with the seventh anniversary of Ben Ali's fall.
Tunisia's Football Association said it was postponing all weekend matches because of the disturbances.