More than 3,200 workers at Chile’s huge Chuquicamata copper mine are to go on strike after union-management talks broke down, state-run miner Codelco the world’s largest copper producer said.

The company said in a statement on Wednesday it regretted the decision of the workers, who decided to reject an improved contract offer after talks aimed at averting the strike.

“The company regrets the decision of the assembly. The offer made by Codelco is serious, responsible and realistic,” it said.

The breakdown follows two weeks of talks between management and three unions representing the workers at the giant mine.

The company’s initial offer, which was rejected, included a 1.2 per cent salary increase and a one-time benefits package worth almost USD 14,000.

Unions said it did not respond to workers’ concerns over medical expenses and pensions.

An improved company offer on Wednesday was also rejected.

Codelco chief Nelson Pizarro had expressed optimism at the outset of the talks.

Located in the harsh Atacama Desert in northern Chile, the Chuquicamata deposit produces around 450,000 tonnes of copper a year.