By Antonio De la Jara and Dave Sherwood
SANTIAGO, July 31 (Reuters) - The union at BHP Billiton Ltd's Escondida mine in Chile, the world's largest copper mine, said on Tuesday that an early, partial vote count on a final contract offer from the Anglo-Australian miner suggests its members will reject the offer and approve a strike.
The union said in a statement that 2,046 of 2,459 union members had already voted in several Chilean cities.
About 90 percent of votes tallied in a partial count of the 2,046 ballots support a strike, the union said.
"We have conducted a partial count in the cities of Arica, Iquique, Calama, Vallenar, Copiapo, La Serena, Vina del Mar and Santiago, and have found overwhelming approval of a strike, around 90 percent of voters," the statement said.
The partial count of votes conducted by the union did not include the key cities of Antofagasta (LON:ANTO) and votes registered at the mine itself, according to the statement.
Workers have until Wednesday to finish voting on the company's proposal, when the union will conduct its official count. After that, either party can call for a period of government-mediated arbitration that could last as long as 10 days.
BHP BHP.AX BLT.L declined to comment on the results of the partial count.
The union vote at Escondida comes little more than a year after a 44-day strike at the mine in 2017 jolted global copper markets and slowed economic growth in the South American country, which is the world's top copper producer.
The company's final offer, presented to workers last week, had included an approximately $18,000 signing bonus, and a 1.5 percent boost to salaries, with increases for inflation, according to a BHP summary of the contract offer viewed by Reuters.
The union in June asked for a signing bonus around twice that now offered by the company, and a salary increase of 5 percent.
A final vote count is expected early on Thursday morning, a union official told Reuters.