The deadline for pay talks between the Freeport McMoRan Copper and Gold mine in Papua and its Indonesian workers has been extended until the end of this week.
Reuters reports a union official as saying little progress has been made so far.
The union, representing about 8,000 employees, has been pushing for substantial wage rises from current levels which are as low as one US dollar 50 an hour.
Virgo Solossa says the positions of the parties are far from reaching agreement.
The workers had earlier gone on strike and Mr Solossa says further strike action is possible.