(REUTERS) -- The union at Freeport McMoRan Copper & Gold Inc's Grasberg mine in Indonesia has halted a return to work after a three-month strike pending the resolution of a local labour dispute, senior union official Virgo Solossa said on Tuesday.

The union said local contractor PT Kuala Pelabuhan Indonesia (PT KPI) must guarantee that no workers who participated in the strike would lose their jobs.

The company says 18 of its workers were sacked and another 101 temporarily suspended in September and October pending further evaluation.