The stoppage would affect production at a mine where 5 percent of the world's copper is produced.
Santiago: The workers' union of Minera Escondida, the Chilean copper mine that is the highest-producing in the world, threatened an "imminent" strike after rejecting the latest proposal from controlling firm BHP.
"The strike is imminent, we have not been able to meet with the company," Carlos Allendes, a union spokesman, told AFP on Saturday.
The stoppage would affect production at a mine where 5 percent of the world's copper is produced.
After nearly six weeks of negotiations with Anglo-Australian company BHP, the nearly 2,500 members of the mine's largest union on Saturday began voting on whether to reject or approve the firm's latest proposal.
Balloting is to continue until August 1, but union leaders have recommended rejecting it.
If the workers do reject the offer, mediation will begin. If an agreement is still not reached, the union could strike again, as happened last year, paralyzing the company for 44 days.
"We have made an effort as a company and we are confident that our workers will consider it," Patricio Vilaplana, Escondida's vice president for corporate affairs, said after the company delivered its latest proposal.
The union is calling for a five percent salary increase and a conflict termination bonus of four percent of dividends received by shareholders last year, or about $34,000 per worker.
The company has increased its initial offer of 13.5 million Chilean pesos to 15 million ($23,000) per worker as a bonus for ending the negotiation.
The mine is located in the Atacama desert at an altitude of about 3,100 meters (10,100 feet).
