By James Attwood and Nathan Gill

Oct. 1 (Bloomberg) — BHP Billiton Ltd. workers at the Spence copper mine in Chile voted in favor of a strike, rejecting a pay offer by the company, a union official said.

Workers in the Spence mine union voted 525 to 1 late yesterday against BHP’s offer, Pedro Marin, president of Chile’s Mining Federation, which represents 8,500 miners, said today in a telephone interview. A unit of Melbourne-based BHP, the world’s biggest mining company, will request a five-day extension to talks stipulated by Chilean law, Ruban Yogarajah, a company spokesman, said today in an e-mailed statement.

Workers are seeking a 5 percent pay raise plus bonuses while the company is offering 2 percent, according to Marin. BHP earned a record $15.4 billion in 2008. The company said Aug. 12 fiscal second-half profit declined 65 percent to $3.26 billion after the recession curbed prices and metals demand.

“There are still opportunities to reach an agreement through dialogue,” Marin said. “If that doesn’t work other measures will have to be taken.”