The Australian Foreign Investment Review Board (FIRB) decided on Monday to delay the decision on Chinese major mining company Chinalco and Australia's aluminum producer Rio Tinto's deal for 90 days, according to report of Australian Associated Press.
Chinalco proposed to buy 18 percent of Rio Tinto in February but will need FIRB approval.
The $19.5 billion investment by Chinalco will give it stakes in a number of Rio Tinto's assets, and increase its interest in the dual-listed miner from nine percent to 18 percent.
The transaction, which has been backed by the Rio Tinto board, will also allow Chinalco to appoint two new non-executive board members to the global miner's board.
Rio said the company will use the capital injection from Chinalco to help tackle the $38 billion debt it incurred by buying Canadian aluminum producer Alcan Inc in 2007.