Unionized workers at Codelco's Chuquicamata operation in Chile voted to go on strike after earlier rebuffing the miner's final contract offer, Reuters reported May 29.

According to the report, 80% of the members of unions 1, 2, and 3 — which represent nearly 3,000 workers and make up over 80% of the workforce at the operation — rejected the final offer, which included a US$14,150 bonus per worker and a 1.2% salary raise. The final deal proposed bonuses that were about US$5,500 less per worker against an earlier offer that was rejected by workers.

Either Codelco or the unions may call for government mediation to try to avoid a strike at Chuquicamata.

The state-run miner began underground mining operations at Chuquicamata in April as part of a 10-year, US$40 billion overhaul of its aging facilities to maintain output amid falling ore grades at its mines.