Union workers at Freeport McMoRan Copper & Gold Inc.'s extended their strike at a massive Indonesian gold and copper mine on Thursday for a second month, the longest strike in the country's mining industry.

About 12,000 of Freeport's 23,000 Indonesian workers have joined the strike that began on Sept. 15, reducing mining, processing and shipping of concentrates from Grasberg, the world's third-largest copper mine.

Miners throughout the developing world have walked off the job this year to demand better pay as corporate profits surged.

Freeport, the world's largest publicly traded copper miner, is also facing a strike at its sprawling Peruvian Cerro Verde mine. Union leaders formally asked Peru's government on Monday to define a wage deal that would settle the strike.

In Indonesia, union official Juli Parorrongan told Reuters a letter on the extended strike had been sent to the company. Freeport officials were not immediately available to comment.

The stoppage has stoked concern of a broader push by workers for a greater share of profits in Southeast Asia's biggest economy. Pilots and supermarket staff have also recently gone on strike.

The mining strike coincided with Freeport's annual term talks with buyers at the London Metal Exchange. Chief Executive Richard Adkerson said on Wednesday the company was unable to make up a production shortfall from strikes in Peru and Indonesia as it already operates at full capacity.

Indonesian union officials and members of the local government and parliament met in Jayapura, capital of remote Papua province where the mine is located, to set up a review team to visit the site soon.

Union officials had planned to continue talks with the company after mediation ended in a deadlock two weeks ago.

Parorrongan said the union regretted that representatives from Freeport were unable to attend in the meeting in Jayapura.

Their absence at today's meeting showed they do not have good intentions to settle this issue, he said. If they can show us data that could back up their argument then we're willing to lower our demand because they can afford it,

The union has lowered its pay rise demand to $12.50 to $37 an hour from $17.5 to $43 an hour. The mine workers' current rate is $1.5 to $3 per hour. Earlier this week, Freeport said they had accepted a mediator's suggestion of a 25 percent increase. But the offer was rejected by the workers.

In the metal market, Europe's steps to help its financial sector and improved outlook on U.S. economic data copper supported copper gains for a second day, after hitting its lowest in 14 months earlier this week.