Chinalco is keen on purchasing a direct minority stake in one of the world's largest undeveloped gold-and-copper mine deposits.

The Aluminium Corp of China "has indicated an interest" in buying a minority equity stake in Ivanhoe or a minority interest in the Oyu Tolgoi project, Rio Tinto said in a US Securities and Exchange regulatory filing.

Canada's Ivanhoe Mines, which has a 66 per cent stake in the Mongolian Oyu Tolgoi project, previously expressed interest in selling a minority stake to a second strategic investor.

Rio Tinto, the project operator, owns an indirect interest in Oyu Tolgoi through its 29.6 per cent equity stake in Ivanhoe Mines.

It is in talks with Ivanhoe to convert its indirect equity stake in the project "into a direct ownership interest," the company said.

"If any arrangement is agreed, it may be a bipartite or tripartite arrangement with" Ivanhoe and/or Rio Tinto, the mining giant said.

Multinational mining and resources group Rio Tinto exercised warrants on June 29 to acquire shares of Ivanhoe Mines, expanding its interest from 22.4 to 29.6 per cent for about $US393 million. It could blow up its claim to 44 per cent if it applies all its warrants and transforms a $US350m ($412m) load into shares.

Rio Tinto has also had discussions about the project with European Bank for Reconstruction and Development, The International Finance Corporation and several others.

The company plans to continue its talks with Ivanhoe, Chinalco, the EBRD, the IFC and other third parties, including the government of Mongolia, which owns 34 per cent of the project.