Chilean copper mine Escondida won't comment on whether it is hiring replacement labourers to maintain output, after striking workers on Monday rejected its latest contract offer, a mine spokesman said Tuesday.

"I can neither confirm nor deny reports that we've hired replacements," Escondida spokesman Mauro Valdes said in response to an article in Tuesday's La Tercera.

"If we had, we're in our legal right to do so."

In a Monday vote, 98% of union members at Escondida rejected a sweetened offer and vowed to prolong the strike.

"We regret that it's come to this point," Valdes said, "but we continue to be open to any dialogue whose genuine objective is to reach an agreement."

According to Valdes, negotiations are at a stalemate.

The union, meanwhile, is still optimistic government mediators will call them back to the negotiating table.

"We're expecting Labour officials to contact us with a date for the next round of talks," said union representative Francisco Aedo.

Now that the strike is in its 16th day, workers can legally abandon the strike and negotiate individually.

When asked if disillusioned workers had approached the company to negotiate individually, Valdes declined to comment.

"Maybe one or two did so, but we haven't had reports of workers abandoning the strike in droves," the union's Aedo said.

On Sunday, Escondida – controlled by Anglo Australian miner BHP Billiton – offered the workers a 4% real wage increase, up from its previous 3% offer, and another 1.3% hike in the fourth year if workers signed a four-year contract.

Additionally, the company offered contract signing benefits totalling 17 million pesos ($32,000), including an unprecedented CLP9.6 million market conditions bonus, a CLP3.4 million end-of-negotiations bonus and a CLP4 million interest-free loan.

While unionized workers often receive end-of-negotiations bonuses, this is the first time mining workers were offered a bonus linked to sky-high copper prices.

In a statement Sunday, the company had said this latest offer was its final.