Freeport-McMoRan Copper & Gold Inc said on Tuesday that production and processing rates at its strike-hit Grasberg nine in Indonesia have fallen below levels needed to meet fourth-quarter sales targets.

The announcement, plus a drop in the copper price, sent the company's shares down 6.4 percent to $37.67 in morning trading on the New York Stock Exchange.

The Phoenix-based company said the Grasberg open pit mine and the adjacent DOZ underground mine were operating at reduced rates using non-striking employees and contractors.

Since Oct. 22, it said, milling operations have been suspended pending repairs to sabotaged pipelines that transport copper concentrate from the mine in Papua to a seaport.

The company said it started repairing the damage but has not been able to gain full access to the affected areas because of road blockages by striking workers.

It suggested it might not achieve fourth-quarter production and sales targets as a result. Freeport has said it expects fourth-quarter sales of 915 million pounds of copper and 305,000 ounces of gold, of which 185 million pounds of copper and 280,000 ounces of gold are expected from Grasberg.

Those estimates were based on fourth-quarter mill throughput averaging 175,000 tonnes per day. But the average so far after one month of the quarter has only been 120,000 tonnes per day, the company said.