Police in Chile used tear gas to scatter hundreds of striking contract workers near a giant state-owned copper mine.
Local media report police detained about 40 strikers near the El Teniente mine, some 88 kilometers southwest of the Chilean capital.
Contract workers at Chile's state-owned copper mining company, Codelco, began their strike on Wednesday to demand bonus payments.
Strike leaders say the 28,000 contract workers deserve a bonus because Codelco has profited from the increased copper prices on world markets.
However, the Chilean government has ruled out making bonus payments.
It is unclear whether the strike will affect Chile's copper production, a main source of foreign exchange.
Some information for this report provided by AP and Reuters.