Rio Tinto Ltd. (RIO) said Thursday iron ore output increased 1% on the year in the third quarter of 2010 to 47.6 million metric tons from 47.0 million tons in 2009.

But U.S. coal production by the world's number-three listed miner fell 49% to 11.8 million tons in the three months to the end of September from 23.3 million tons in the same period last year.

The hard coking coal used in steel mills rose 17% to 2.4 million tons from 2.1 million tons but other Australian coal sank 14% to 5.2 million tons from 6.1 million tons.

Mined copper production also fell in spite of booming prices for the commodity, with production down 19% to 159,700 tons from 197,200 tons.

Declining ore grades at the Escondida mine, the world's largest, in which Rio Tinto has a 30% stake, meant production at the site in Chile fell 6% on the year.

The company said in a statement it expects its full-year share of iron ore production to total 179 million tons, while mined copper would hit 660,000 tons over the year. It added that Alumina production would come to 9.4 million tons while aluminum would reach 3.8 million tons. Australian hard coking coal production is expected to be 9.5 million tons, semi-soft coking coal 3.3 million tons and thermal coal 19.1 million tons.

-By David Fickling, Dow Jones Newswires; +61 2 8272 4689; david.fickling@dowjones.com