The accident happened today morning at the Grasberg mine in remote Mimika district, said Papua police spokesman Lt. Col. Gede Sumerta Jaya. A search was underway, but the fate of the trapped workers was unclear, he said.
The mine is owned by Phoenix, Arizona-based Freeport-McMoRan Copper & Gold Inc. A written statement from PT Freeport Indonesia, a subsidiary that runs the mine, said a tunnel in the underground training area collapsed. It did not say how many workers were involved, or whether there were injuries or fatalities.
Thousands of workers are employed at the mine, which has been plagued by violence since production began in the 1970s. In 2011, production was crippled when 8,000 unionized employees walked off the job after demanding higher pay.
The four-month strike ended after the company agreed to a 37 percent wage hike and improved benefits. The restive province holds some of the world's largest gold and copper reserves.