Clashes broke out in the southern Tunisian city of Gabes on Wednesday during a rally by protesters denouncing decades of pollution and environmental neglect.
The demonstrators had marched onto a phosphate-processing plant of the Groupe Chimique Tunisien when police fired tear gas to disperse them.
A number of people were injured in the clashes.
The protests were triggered by a recent gas leak that sent dozens to the hospital with respiratory issues, including children.
While the incident was contained, it has revived deep anger over
long-standing health and environmental impacts tied to the phosphate industry.