Riot police used tear gas on Friday to quell violent street protests in Bolivia’s largest city, the latest in three weeks of unrest over calls for a new census.

In central Santa Cruz, a key hub of the energy industry in Bolivia’s tropical lowlands, vendors and public transport workers set fire to tires on streets and threw stones at opponents of left-wing President Luis Arce.

TV footage showed a Farmers Union office being looted and burned to the ground.

Authorities on Friday offered no official tally of arrests or injuries sustained in the violence.

Santa Cruz is a stronghold of centre-right political forces opposed to the Arce government. Some residents there, who claim the region pays more in taxes than it receives in services, are calling for a new census to capture the flow of migrants into the lowlands. The last census was in 2012. The next census is not planned before 2024.

If a new census measured that the region’s population had grown, it would receive more federal funding and more seats in Congress.

The Arce government said four people were killed and 178 injured in unrest in Santa Cruz over the past three weeks.

Santa Cruz provincial right-wing governor Luis Fernando Camacho said protesters on Friday “were attacked by police and the MAS, the ruling party of the Movement for Socialism in Arce.