SANTIAGO – Unionised mine workers in Chile, the world's top copper producer, warned on Thursday that health should take precedence over output, one day after State-run Codelco's unions threatened a walkout at some of its operations.

Workers with the Federation of Copper Workers said there had been an "alarming" spike in coronavirus cases at some mines, one week after a miner at the company´s massive Chuquicamata mine died from Covid-19.

"This is a general warning, in case the administration does not take the measures," Liliana Ugarte, head of the Chuquicamata 2 union, told Reuters on Thursday. "The lives of our people are more important than any production targets."

Codelco declined to comment on the federation's statement.

Regional mining officials told Reuters they had inspected Chuquicamata and spoke with workers there on Wednesday to verify compliance with health safety requirements.

"All the protocols are being applied accordingly," said the regional government representative for mining, Alex Acuña, in a video seen by Reuters.

Mounting worker concerns come as South America has increasingly become the new front in the global coronavirus pandemic, with new cases cresting at 5 000 a day in Chile and deaths from the disease surpassing 2 600. Output from its copper mines, however, has been largely unaffected.

Codelco has been forced to scrap some contract work at its operations, shelved construction projects and implemented measures like longer shifts to prevent the spread of the coronavirus.

Mine workers at BHP´s Escondida copper mine, the world's largest, say its operations in northern Chile have complied with safety protocols.

Patricio Tapia, head of the Escondida workers union, told Reuters the mine had registered just 98 infections among nearly 10 000 workers. Nearly 600 workers with underlying conditions, he said, had been asked to stay home to minimize risk.

"Health, and then production," Tapia said. Escondida has boosted output by 9% in 2020. In April, the mine churned out 102 600 t of copper, up 11.4% from a year earlier, according to Chile state copper agency Cochilco.

Chile said in May its copper industry ranks among the least affected globally by the pandemic, anticipating just a 1% reduction in output.