Aluminum Corp. of China, or Chinalco, said it expected Australia to extend a review of its proposed US$19.5 billion investment in Rio Tinto Ltd. (RTP), and that it doesn't see any biased stance from the country's Treasury department.

The extension of the review by 90 days is "standard procedure" and was expected because of the deal's size, complexity, and sensitivity, Chinalco said in a statement posted on its Web site Monday.

Australia's Treasury department confirmed the extension Monday to "enable due consideration" of the proposed deal. A 90-day extension of an initial 30-day review period is normal procedure under the Australian system when more time is needed by the Foreign Investment Review Board for its deliberations.

"Chinalco will continue to cooperate with the Foreign Investment Review Board," the company said in the statement.

-Juan Chen contributed to this story; Dow Jones Newswires; 8610 6588 5848; juan.chen@dowjones.com