(REUTERS) -- Freeport McMoRan Gold & Copper Inc's Indonesia's unit said on Wednesday it continued to ramp up production at its Grasberg mine where workers on Tuesday halted a gradual return at the end of a three-month strike.

Freeport Indonesia continues to ramp up production and work with the union on worker mobilization, spokesman Ramdani Sirait said in an email to Reuters. Freeport gave no production figures.

For production to reach its optimum level at the world's second biggest copper mine, thousands of workers must be transported to Grasberg, which lies in the central highlands of Papua island in eastern Indonesia.