Tunisian security forces have arrested 632 people during riots that have gripped the North African country for several days, the interior ministry says.
Demonstrators took to the streets of the capital Tunis and other cities on Sunday evening.
The protests turned violent as clashes erupted between the crowds and police forces.
“Security forces faced groups of youths and minors, which often consisted of 20 to 30 people. The level of violence was high,” ministry spokesman Khaled Hayouni said.
He refused to describe them as protests, saying they consisted of “criminal acts and looting”.
Security personnel were seriously injured, he said.
Demonstrators have defied a four-day lockdown and curfew, imposed since Thursday to slow the spread of coronavirus, and have taken to the streets every night since Friday protesting economic hardship.
The protests spread after a video was posted online last week showing a police officer assaulting a shepherd.
Violence on Sunday evening prompted the defence ministry to deploy its army forces in the cities of Sousse, Bizert, Kasserine and Siliana to support police forces and protect state facilities, a ministry spokesman said.
In the capital Tunis, police forces used tear gas to disperse protesters, eyewitnesses said.
Videos shared on social media showed protesters blocking roads and setting tyres on fire while security forces tried to chase and disperse the demonstrators.
The protests come as Tunisia marks 10 years after the uprising that toppled long-time dictator Zine El Abidine Ben Ali.
Since then, the country experienced an economic slowdown due to public unrest and ensuing attacks by militant insurgents.
The coronavirus pandemic worsened Tunisia’s ailing economy.