SHANGHAI, July 28 -- Aluminum Corporation of China Ltd., the nation's biggest producer of the metal, suspended its shares from trading pending an announcement on an "important discussion."

Shares of the company that's known as Chalco are expected to resume trading in Hong Kong and Shanghai on July 30, the Beijing-based company said in a statement.

Chalco's parent company, known as Chinalco, is in talks with Rio Tinto Group to buy a stake in the $4.6 billion Oyu Tolgoi mine in Mongolia or the U.K. company's partner in the project, Ivanhoe Mines Ltd., London-based Rio said July 7.

Chinalco has "indicated an interest in acquiring a minority equity stake in the company or acquiring, from the company, a direct minority ownership interest in the Oyu Tolgoi project," Rio said at the time in a U.S. Securities and Exchange Commission filing, referring to Ivanhoe.

Rio spokesman David Luff wasn't immediately available to comment when contacted today.

Rio is working to repair relations with Chinalco, its largest shareholder, which were soured last year when it scrapped a $19.5 billion investment by the Chinese company and four Rio employees were arrested in Shanghai. Ivanhoe Deputy Chairman Peter Meredith said in May that the company may bring in another partner to the copper and gold project and it made sense for Chinese interests to study an investment.

Ivanhoe spent more than six years negotiating an accord with Mongolia over the project, which Rio has described as the world's largest untapped copper and gold resource. Ivanhoe said in January it hired Citigroup Inc. to study options, including debt and equity offerings and asset sales.