Workers at the world’s biggest copper mine in northern Chile downed their tools over the weekend as part of an indefinite strike over unmet contract demands.

About 2,300 workers of the Escondida mine, under majority control of British-Australian giant BHP Billiton, had launched a stoppage over unresolved disputes such as the failure to reach agreement over annual bonuses.

Workers held peaceful marches late on Friday, while about 1,000 of their colleagues worked at the mine on Saturday.

The rest chose to stay home instead, workers spokesman Marcelo Tapia told AFP.

“The situation remains the same. We are continuing the indefinite strike. We want to have a dialogue with the company, but standing, not kneeling, and a discussion that is constructive and addresses our proposals,” he added.

Miners say their bonuses have dropped up to 70 per cent, which the company blames on lower production and decreased metal concentration, or ore grade.

Salaried workers are also demanding that bonuses tied to record copper prices be doubled.

The work stoppage means BHP Billiton stands to lose some $US30 million ($A27.77 million) – or 3,000 tonnes of copper per day, according to estimates.

The mine, which produces over a million tonnes of copper per year, is located in Antofagasta, a city of some 3,100 metres in altitude. BHP Billiton holds 57.5 per cent of the mine’s capital.

Chile is the world’s biggest producer of the red metal, with 5.6 million tonnes per year.

AFP