Rio Tinto has announced plans to construct the underground section of the $5.4bn Oyu Tolgoi copper and gold mine in Mongolia in 2015 with an investment of up to $300m.
Reuters quoted Mongolian Prime Minister Chimed Saikhanbileg as saying that the company plans to begin second phase of construction at the mine in 2015.
The latest development represents progress for the long-stalled mine, which is expected to reach full capacity in 2021 and boost Mongolia's economy.
According to Saikhanbileg, the next phase of the Oyu Tolgoi mine will be financed by 14 different international organisations and banks, including the World Bank's International Finance Consortium and the Multilateral Investment Guarantee Agency.
The mine still requires an additional $4bn in financing and is expected to produce an average of 430,000t of copper and 12.05t of gold a year.
In a separate announcement, Rio Tinto has completed the sale of its 78% interest in Murowa Diamonds and 50% interest in Sengwa Colliery.
The overall management of both units would be assumed by Zimbabwean mining company RioZim, which already owns a 22% interest in Murowa Diamonds and a 50% interest in Sengwa.
Rio Tinto Diamonds and Minerals chief executive Alan Davies said: "Rio Tinto remains committed to the diamond industry and is focused on operating its two world-class underground mines whilst obtaining the approvals for its advanced diamond project in India."
Production from the open-pit Murowa Diamond mine located near Zvishavane in south-central Zimbabwe commenced in 2004 with a current capability of around 400,000 carats a year.
Since 2004, the mine has produced more than million carats.
Image: Oyu Tolgoi project, Copper and Gold Mine in South Gobi. Photo: courtesy of Brücke-Osteuropa.