Miner BHP has formally requested a period of government mediation with the union at its Escondida copper mine in Chile, the world's largest, prompting the union to postpone the start of a strike approved by workers.
The two parties will meet together with a government mediator on Tuesday, and talks will continue until August 13, according to an internal union document.
If there is no agreement by then the strike would begin on August 14, but talks could be extended by another five days if both parties agree.
Earlier on Monday, the union said it had begun preparing for a strike. Workers last week rejected the company's final wage offer and approved a strike, but Chilean law allows either party to call for a period of government mediation, a last effort to reach agreement ahead of a walk-off.
"We have asked authorities for mediation because we want to reach an agreement and because we know that no one wants a strike," Patricio Vilaplana, BHP vice president for corporate affairs, said in a statement.
Last year, a 44-day strike at the mine jolted global copper markets and slowed economic growth in the South American country, which is the world's top copper producer.
BHP's final contract offer two weeks ago included a signing bonus of about $US18,000 and a 1.5 per cent boost to salaries, with increases for inflation.
But the union had asked for a signing bonus of almost double that offered by the company, and had requested a salary increase of 5 per cent, leaving a wide gap between the two sides.
Despite the mounting tensions at Escondida, copper prices slid on Monday as investors worried about the damage to global economic growth from the trade dispute between the US and its trading partners.
Escondida produced 925,000 tonnes of copper in 2017.