Rio Tinto polishes image of giant Oyu Tolgoi mine in Mongolia

Inside the brand new information centre at Oyu Tolgoi mine, the resident guide shuffles between hi-tech displays of flashing lights, models and videos as he explains to a group of students the staggering size of Mongolia's biggest infrastructure project.

"The ore body at Oyu Tolgoi contains 24.7 million tonnes of copper and 1087 tonnes of gold. It can be mined for 69 years," Munkhbayar Ganbat announces, showing off a scale model of the 39 kilometre long underground mineral reserve, which has been a source of controversy for nearly a decade. It's balanced over a schematic of Manhattan, as a way to indicate the sheer size of the deposit.

"The general public has high expectations from this project. But they have insufficient information, which is why we created this centre," Munkhbayar later told the Sunday Morning Post.

The information centre is part of a campaign by Rio Tinto to win over the hearts and minds of the Mongolian people, who want the country to receive a greater share of its natural wealth. The project is 66 per cent owned by Rio Tinto and Turquoise Hill Resources, with the remaining 34 per cent in the hands of the Mongolian government. The terms, established in a 2009 investment agreement, will exist for 30 years, after which time Mongolia has the right to negotiate for a 50 per cent stake.

But three years after the deal was inked, many here are feeling buyers' remorse and calling for the contract to be rewritten. Twice in the past year, backbench members of parliament have issued a letter to Prime Minister Sukhbaatar Batbold ordering a renegotiation of the terms so Mongolia can grab its half as soon as the investors recoup their US$6 billion start-up investment.

Rio Tinto has held its ground, saying that the time for negotiation has passed. But its defensive position comes with a dose of soft power, too. In addition to the information centre, the Anglo-Australian firm is spending more than US$2 million on environmental and social projects.

These have included the renovation of the hospital near the mine site, a vaccination programme for the local population and a new dental clinic. Rio Tinto also donated US$150,000 to rebuild the local Buddhist monastery, which Stalin's thugs had destroyed in 1937.