Workers at BHP Billiton's Escondida site, the world's biggest copper mine, voted to prolong a strike that drove up metal prices last week amid concern that other mines in Chile may join the action.
Workers seeking higher production bonuses and better job conditions agreed to extend a one-day stoppage onJuly 22 after talks with management broke down, a union leader said.
"The company has indicated it doesn't want to talk anymore with us so we'll remain halted," said Salomon Alcaino, a union director.
He spoke after a meeting of union officials representing workers at mines owned by Anglo American, Freeport-McMoRan Copper & Gold and Xstrata.
The Chilean mining union movement is in "a state of alert" and may join the walkout if Escondida's demands aren't met, he said.
The strike is "illegal" and "the company is implementing an action plan to ensure the safety of its workforce and the integrity of its operations," said Kelly Quirke, a spokeswoman for BHP, yesterday, without specifying the plan.
Workers want a bigger share of profits after copper soared 38 per cent in the past 12 months on growing Chinese demand.
Miners at Codelco, Chile's state-owned producer, carried out a 24-hour strike on July 11.
Copper rose in London and New York on the threat that the strike at Escondida may spread to other mines, said Daniel Briesemann, an analyst at Commerzbank in Frankfurt, in a July 22 report.
Futures for September delivery rose US2.65c, or 0.6 per cent, to US$4.41 a pound in New York on July 22.
Melbourne-based BHP fell 0.7 per cent in Sydney trading yesterday to A$43.12 at 11:50am local time.
BHP owns 57.5 per cent of Escondida and its share of output in the year through June was 390,500 tonnes. Smaller rival Rio Tinto Group owns 30 per cent.
