Freeport-McMoRan Copper & Gold Inc said Wednesday the strike at its vast Grasberg mine in Indonesia has hurt production and it is unlikely to meet third-quarter gold and copper sales estimates.

The strike, which started Sept. 15, has limited mining, milling and concentrate shipping activities, but about half of the 8,000-member work force, primarily contractors and non-union staff employees, have reported to work, the company said on Wednesday.

The estimated impact on production is about 3 million pounds of copper and 5,000 ounces of gold for each day of the work stoppage, it said.

Freeport said its consolidated third-quarter sales estimates of 940 million pounds of copper and 415,000 ounces of gold are expected to be hurt by the strike.

The company said it is developing revised operating plans, to begin increasing mining and milling rates with a reduced work force.

The company's stock was down 35 cents at $38.20 in premarket trading on the New York Stock Exchange.