Labor talks at Escondida - which is controlled by BHP Billiton (>> BHP Billiton Limited) (>> BHP Billiton plc) with a 57.5 percent stake, while Rio Tinto (>> Rio Tinto Limited) (>> Rio Tinto plc) owns 30 percent - are seen as a benchmark for the copper industry at large. The last wage talks four years ago, when copper prices were considerably higher, ended with Escondida offering each worker a bonus worth some $49,000, the highest ever offered in Chile's mining industry.

"Today, we're starting the process of normal collective negotiation...with the clear conviction that we're not asking for favours nor gifts nor anything we don't deserve, but rather we're asking that the company deliver what belongs to us," Escondida's main union, which represents 2,492 workers, said in a statement.

On Friday, workers at Chilean state-owned Codelco's [COBRE.UL] Chuquicamata copper mine accepted an early wage deal, putting to rest what some industry insiders feared would be prolonged, tense talks.

At those negotiations, which are also considered to be predictive for industry at large, workers signed a 27-month contract which offered no salary increase, but included per-worker bonuses of some 4.3 million Chilean pesos ($6,390).

(Reporting by Gram Slattery; Editing by Andrew Hay)