Jayapura:
A tunnel at a mine in the remote east of Indonesia caved in Tuesday with around 30 workers inside, the US operator and police said.
Rescuers did not know whether those inside were alive or dead following the accident at Freeport-McMoRan's Grasberg, one of the world's biggest gold and copper mines which is high in the mountains of rugged Papua province.
It is the latest problem for the mine, which was hit by a major strike in 2011 that crippled production.
"A tunnel in the underground training area collapsed, trapping a number of employees," said a statement from the Indonesian subsidiary of Freeport.
"We cannot confirm the number of injured or trapped individuals nor whether there have been any fatalities."
Local police chief Jermias Rontini said that more than 30 people were believed to have been inside when the tunnel collapsed.
"The evacuation team and the police are still outside the tunnel because we are worried there may be further collapses or poisonous gas," he said.
Freeport added that the rescue operation at the mine "is difficult and will take some time to complete".
The company did not disclose the nationalities of those trapped, although the vast majority of the more than 24,000 workers at the mine are Indonesian.
Neither police nor Freeport said why the accident happened.
The 2011 strike lasted three months and crippled production, only ending once the firm agreed to a huge pay rise.
The industrial action sparked a wave of deadly clashes between police and gunmen around the mine, with at least 11 people, all Indonesians, killed.
Earlier this month, some 1,100 workers employed by Freeport contractors staged a three-day strike over pay but it caused only minimal disruption to production.