Bolivia's largest city Santa Cruz marked three weeks of protests on Friday as demonstrations over a delayed census boiled over.

Santa Cruz, a relatively wealthy farming hub and opposition bastion, has in recent days grinded to a halt due to a general strike demanding that authorities hold a census next year before elections in 2025.

On Friday, protesters clashed with government-aligned groups, with local television showing altercations involving Molotov cocktails, motorcycles, firecrackers, stones and sticks.

The three weeks of protests have left four people dead and more than 170 injured, the government reported. It blamed the escalation of violence on Santa Cruz governor Luis Fernando Camacho, who initiated the strike on Oct 22 along with other opposition groups.

Economy Minister Marcelo Montenegro on Friday said the strike, which has worsened food shortages and sent already high prices soaring, has cost some US$700 million (RM3.29 billion).

Regional and opposition groups say the socialist government in La Paz delayed the census because it would result in them being allotted more seats in Congress and more state resources.

In an opinion column, former economy minister Oscar Ortiz noted that recent years of migration from rural areas to Santa Cruz could disadvantage the governing Movement to Socialism party in congress.

"Demographic trends don't favour them," Ortiz said. "It is going to be increasingly difficult for them to guarantee the legislative majorities they have enjoyed in the past."

- Reuters