Timika, Papua – Workers at Freeport McMoran Copper & Gold Inc's mine in Indonesia may delay returning to work, despite a deal to end a three-month strike, in the absence of a decision on the removal of about 100 workers at a local unit, a union official said on Monday.

The workers at Freeport Indonesia's Grasberg mine in the eastern province of Papua were supposed to gradually return to work this week to end the strike that has crippled output and exports from the world's second-biggest copper mine.

They had agreed to a deal with management earlier this month on a pay rise of about 40 percent to end the three-month strike that crippled the company's production.

Some workers held a traditional stone burning ritual and removed a road blockage over the weekend near the mine, marking the end of the longest running strike in recent Indonesian history.

But the agreement is at risk as the local unit, Kuala Pelabuhan Indonesia, had failed to guarantee that 119 workers, who were suspended during the strike, would be rehired, said Virgo Solossa, a senior Freeport Indonesia union official.

KPI has a total of 2,100 workers, mostly at the port which handles copper shipments of Freeport McMoran Copper & Gold Inc's Indonesian unit.

Juarsa Oemardikarta, senior manager corporate and administrative support at KPI, said 18 workers had been sacked and another 101 temporarily supended in September-October until further evaluation.

Grasberg workers may also stay away from the mine until there is a decision on another 473 KPI workers who had to sign a disciplinary statement before resuming work.

Solossa said the union had asked KPI to scrap the dismissal and start afresh following the recent deal to end the strike. "Potentially, this would have a huge impact on our agreement recently," Solossa said.

Solossa said the union had mobilized nearly 250 workers to return to the mine on Monday, but they were still not back at work. Most workers at the Grasberg mine are on holiday for Christmas.

KPI was in the process of renewing its two-year agreement with its workers when the strike started on Sept. 15, Oemardikarta added. Freeport Indonesia declined to comment on the matter.

The strike at Grasberg mine harmed Freeport's total production and led the firm to declare force majeure on exports in October, helping lift global prices.