The world's largest privately-owned copper mine could see production halted next week, as workers threaten strike action after rejecting a pay offer.
Copper mining is a massive business
Labour relations at the Escondida mine in Chile have deteriorated as staff hold out for a 13% salary rise and a 16m peso ($16,900; £8,900) bonus.
The mine operators' latest bid had been a pay increase of 3% and a bonus of 8.1m peso, double their previous offer.
Workers said a strike could still be averted at talks late on Thursday.
"If there is real good will to solve this, a strike may be averted," said workers' spokesman Pedro Marin.
Mr Marin said that the latest pay proposal was massively and absolutely rejected by the mine's 2,000 workers.
Should the talks fail on Thursday and Friday then the strike would start on Monday.
The Escondida copper mine is 57.5%-owned by BHP Billiton, while fellow miner Rio Tinto owns 30%. The remaining stock is held by a Japanese-led consortium, with a small stake in the hands of International Finance Corp.
The labour dispute comes as world commodity prices have surged, partly due to a surge in demand for metals and partly as supplies become squeezed.
Analysts said that any disruption to output at Escondida, which is expected to produce 1.4 million tonnes of copper this year, may lead to copper prices rising on the international market.