SANTIAGO, Región Metropolitana de Santiago (AFP) - Workers staged a 24-hour strike on Wednesday at Escondida Mine in northern Chile, the world's largest private copper mine.

The strike began after management refused to pay an annual bonus that is not covered in workers' contracts, which last year totalled approximately US$5,000 (S$6,400) per worker.

The mine, which employs an estimated 2,500 workers, is majority owned by BHP Billiton of Australia.

"This is a bonus that the company sets at its discretion and that it now does not want to pay. We're not asking for a specific figure, but to be paid like every year," Mr Marcelo Tapia, spokesman for the Escondida Workers Union, told the newspaper La Tercera.

Mr Tapia said workers are also asking for a system to keep track of overtime and the removal of surveillance cameras from inside mining trucks.

Management had no immediate comment on the strike.

The workers union said it has not ruled out extending the 24-hour protest.

The Escondida Mine, whose 2012 earnings totaled approximately US$3.167 billion, a 14.2 per cent increase from the previous year. Last year the mine produced over one million metric tons of copper.

The mine is located in the city of Antofagasta, 1,300km north of Santiago. BHP Billiton owns 57.5 per cent of the operation, while Rio Tinto owns 30 per cent, JECO Corporation owns 10 per cent and JECO 2 Ltd owns 2.5 per cent.

Chile is the largest copper producer in the world, providing nearly one-third of global supply.