Xstrata Copper (XTA.L: Quote) said on Monday it would request mediation after workers at its Lomas Bayas copper deposit in northern Chile voted for strike action when collective wage agreement talks failed.

In a vote on Sunday, 97 percent of workers at the deposit rejected the company's proposal of a 3.7 percent salary hike. They were demanding a 6 percent increase, union leaders said.

We are confident that we will reach a good deal, both for the union workers and for Lomas Bayas, to ensure the future viability of this operation, Carlos Noemi, head of human resources at Xstrata Copper's Norte division, said in a statement.

Via government mediation, Xstrata can extend the talks for another five working days.

Pedro Marin, president of the Chilean Mining Federation which groups workers from some of Chile's largest copper mines, earlier held out little hope for an amicable solution.

They are (offering) around 50 percent of what the workers are aiming for, so it is most likely they won't reach a deal and the strike will go ahead, Marin told Reuters.

The Lomas Bayas deposit, which is located in Chile's Atacama desert, has an annual output capacity of around 75,000 tonnes of copper. (Reporting by Manuel Farias; Editing by Simon Gardner)

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