Rio Tinto Ltd. (RTP) plans to spend US$3.1 billion on expanding its iron ore production capacity in Western Australia's Pilbara region to 283 million tons a year, the company said Wednesday.

Rio Tinto said it would hit the target, which compares to a current rate of around 200 million tons a year, during 2013, with further growth targeted at 333 million tons a year by mid-2015.

In its half-year results in July, the company announced plans to commit around US$13 billion to new capital spending by the end of 2011, the bulk of that dedicated to iron ore.

"This is the largest mining project ever undertaken in Australia and highlights the quality of our growth options," said Sam Walsh, Rio Tinto's iron ore and Australia chief executive.

"The single best creator of value for Rio Tinto shareholders is to move more Rio Tinto tons through an expanded Cape Lambert. Today we have committed further funds to doing just that."

The company said the investment would pay for new port and rail infrastructure around Cape Lambert. The company has announced US$6 billion of fresh investment in the Pilbara since July, of which Rio Tinto accounts for US$3.9 billion.

The company's minority partners in its Pilbara operations are Sumitomo Corp., Mitsui & Co., and Nippon Steel Corp.

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