Jakarta – Freeport-McMoRan Copper & Gold Inc reached a tentative agreement with Indonesian union workers on Wednesday over wages and pensions, a union official said, raising hopes that a strike will be averted with just two days left of talks.

Contract talks between workers and management at Freeport's Grasberg mine in Papua, which is the world's second-biggest copper mine, have entered their fourth month and are scheduled to end on Friday with or without a deal.

"We can say that in principle we have reached an agreement on pay talks with Freeport management including on wages and pensions," Juli Parorrongan, spokesman for the workers' unions, told Reuters. "The final agreement has not yet been reached because there are still several points to be discussed further."

He said strike action was still an option for the union if a final agreement was not reached this week. Freeport's Indonesian unit could not be reached immediately for comment on Wednesday.

The negotiations, which are seeking agreement on workers' wages, benefits, rights, obligations and pensions, were suspended in May when a tunnel collapse killed 28 people, and then resumed in June.

Late last month, the talks stalled despite the high level involvement of Freeport Indonesia CEO Rozik Soetjipto and Freeport CEO Richard Adkerson.

"All the points that we have agreed with Freeport management have to be written into a joint work agreement between both the union and Freeport," said Parorrongan. "As long as the new joint work agreement is yet to be signed, everything can happen."

Freeport Indonesia employs about 24,000 workers, including contractors and staff. About three-quarters are union members.

Relations between Freeport and unions have been strained in recent years following a three-month strike in 2011, May's deadly tunnel collapse and a series of minor spats.