More than 7,000 workers from US company Freeport McMoRan's massive gold and copper mine in Indonesia's western Papua region started a week-long strike on Monday to demand better wages.
"We want a bigger salary so that we can afford to have a better life," Frans Kaweai, a protester, told AFP at the site entrance.
"We started our strike from today because the management refused to agree to our demands," he added.
Hundreds of police officers have been deployed to secure the mining area.
"Our personnel will provide security to prevent the protest from turning violent," Mimika police chief Deny Edward Siregar told AFP.
Freeport's spokesman Ramdani Sirait said the protest had not affected production but urged staff to return to work "while this issue is being resolved to avoid impacts to employees and the company".
"The company is working diligently with the union and employee leadership to resolve this work stoppage," he said in an e-mailed statement.
The Freeport mine sits on some of the world's richest gold reserves and the US company's local subsidiary is the largest single taxpayer to the Indonesian government.
Papua, a resource-rich region on the western end of New Guinea island, has been the site of a low-level separatist insurgency since its incorporation into Indonesia in the 1960s.