The union will vote on the offer later in the day, and the government-led mediation period will now last until Dec. 18, union leader Luis Redlich said, which would give the company time to come up with another offer if needed.

If the two groups fail to come to an agreement, workers will go on strike beginning on Dec. 19, he said.

The nearly 400 employees represented by the union overwhelmingly rejected an earlier contract proposal last month, looking to make up for lower production-linked bonuses and to improve working conditions.

In 2022, Centinela produced 247,600 metric tons of copper, according to government data.