(MENAFN) Rio Tinto, the top British-Australian multinational mining corporation has financed a massive expansion of its giant Oyu Tolgoi mine in Asian Mongolia, according to the latest reports.

Additionally, the mine, which has a total copper and gold reserves estimated at 2.5 billion tones, inked a whopping USD4.4 billion deal with global financial institutes and 15 commercial banks.

Moreover, Oyu Tolgoi initiated work from an open-pit mine 2 years ago, but the financing paves the way for its 2nd and more valuable phase underground, where the firm says 80 percent of reserves lie.

The project, forecasted to contribute up to one third of the Mongolia's GDP once fully operational, has been suffering with disputes stalling progress on the underground phase for almost 3 years.