The Araguaia project will initially produce up to 14,500 tonnes of nickel per year.

President Andres Manuel Lopez Obrador said investigations into those responsible for the mine's safety will come only after the rescue effort.

They became trapped on Wednesday after three wells at the coal mine overflowed, causing an inner wall to collapse.

Glencore warned that Europe’s energy crisis poses a substantial threat to supply.

Some 92 soldiers were working at the scene, as well as specialists and rescue dogs.

Although no one was hurt in Wednesday's "operational incident," Codelco said it had launched an investigation to determine the cause.

Lundin said Monday it had halted development work near the site, but that the sinkhole didn’t affect the community, workers or its annual output guidance.