Rio Tinto (LON:RIO) said its Oyu Tolgoi underground copper mine in Mongolia had taken a step forward with the signing of a US$4.4bn funding deal.
Rio and its partners have secured project finance for the mine from international financial institutions and export credit agencies representing the governments of the US, Canada and Australia, along with 15 commercial banks.
Earlier this year, Rio, Turquoise Hill Resources and the Mongolian government agreed a mine development and financing plan.
Rio Tinto and other shareholders will draw down the new funding after updating the feasibility study, including the revised capital estimates, and securing all necessary permits for the pit.
Rio Tinto Copper & Coal chief executive Jean-Sébastien Jacques said "This project finance agreement is significant in the industry and is the next important step towards further development of the world-class Oyu Tolgoi mine in Mongolia.
"Long-term copper fundamentals remain strong and Oyu Tolgoi as a tier one asset will be a globally important source of supply as the market moves back into structural deficit over the next few years."
Broker Investec said the funding is expected to more than double output at Oyu Tolgoi. Shares in Rio rose 30.5p, or 1.6%, to 1878.5p.