Rio Tinto says it has no plans to delay the big Mongolian Oyu Tolgoi copper-gold project and denies media reports the $3 billion development may slow.

Rio Tinto Ltd/Plc is not planning to delay construction of the Oyu Tolgoi copper and gold mining project in Mongolia, denying media reports it was considering such a move with joint venture partner Ivanhoe Mines Ltd.

The Sydney Morning Herald said on Monday that Rio had warned construction of the $3 billion project, touted as one of the world's biggest finds, may proceed at a slower pace that planned even if the Mongolian government signs a long-awaited investment agreement within days.

The report was based on an interview last week with Rio Chief Executive Tom Albanese, the paper said.

"Rio Tinto remains fully committed to the Oyu Tolgoi copper gold project in Mongolia. Rio Tinto and Ivanhoe Mines have spent more than US$1 billion on the project to date and underground construction has continued while we await the finalisation of the Ivanhoe agreement," Albanese said in a statement emailed to Reuters on Monday.

Albanese said Oyu Tolgoi remained one of the "most attractive undeveloped copper-gold projects in the world," adding additional construction stages would be planned carefully, including reviewing costs in the current economic conditions.

Miners worldwide are revising plans for projects that are only viable when metal prices are high. At around $3,700 a tonne MCU3, copper prices are running at less half the price a year ago. Gold prices <XAU=> stand around $935 an ounce versus $972 two months ago.

Ivanhoe last week said a draft investment agreement to develop the project was endorsed in principle by Mongolia's cabinet and would be presented to the national parliament.

The mine is expected to produce an average of 440,000 tonnes of copper and 320,000 ounces of gold a year over a 35-year mine life.

Mongolia is reportedly seeking a 34 percent stake in Oyu Tolgoi. Once an agreement is reached, Rio's stake will double to 19.8 percent from 9.9 percent now.