Police in Chile have used teargas and water cannons to disperse striking, stone-throwing workers at the world’s biggest copper mine in the northern part of the country.

Clashes erupted at the Escondida copper mine on Wednesday as protesters started throwing stones and tried to block a highway, which briefly caused traffic and cut off southern access to the Chilean city of Antofagasta.

The workers set barricades on the main roads to the mine and set tires on fire, which eventually led to police intervention.

Escondida copper mine miners on strike block a road in Antofagasta, Chile, March 1, 2017. (Photo by AFP)

“We are urging these people to think again about what they are doing and open up the highway, so as to allow free transit for the general public who goes through this area,” Antofagasta Lieutenant Colonel David Estay Torres said to reporters during the Wednesday clashes.

“And the truth is that we had to proceed according to norms and existing legislation; and as of this moment, we have had two interventions, but we haven’t been able to open up the transit,” he added.

The miners had launched a three-week strike early last month in reaction to disagreements over benefits and changes in their shift patterns. The striking workers accused the mining company, BHP Billiton, of failing to deliver payments.

The company, in turn, has blamed the miners for causing damage to equipment and installations.

Both sides have yet to reach an agreement over the issues. A government-led attempt at mediation failed last week.

Escondida, located in the copper-rich Antofagasta region, in northern Chile, supports just over 10,000 full-time jobs.