Jakarta – Workers at a Freeport McMoran Copper & Gold Inc Indonesian mine on Tuesday halted their gradual return to work one day after gunmen shot two contractors dead on the road to the Grasberg mine, a union spokesman said.

It was unclear whether the halt also affected production at the mine in the central highlands of Papua, an island in eastern Indonesia.

"This terror is like a monster for us, the workers," union spokesman Juli Parorrongan said. "Every day the workers ask who is going to be the next victim," he said, adding that no more workers would return until police ensure the safety of the mine road.

Workers have slowly returned to Grasberg in the wake of a three-month strike over pay that crippled production at the world's second-biggest copper mine and shook labor relations in Indonesia, southeast Asia's largest economy.

Around 2,000 workers have returned to Grasberg and around 7,000 others are waiting to be transported by bus to the mine, said Parorrongan by telephone, adding that some other workers did not join the strike.

There have been scores of shootings by unidentified snipers around Freeport in recent years, with victims including workers, illegal miners, and -security officers.