Australia's Foreign Investment Board will extend its review of top Chinese aluminum maker Chinalco's $19.5 billion investment in global miner Rio Tinto for up to 90 days, a government notice said on Monday.

FIRB put an interim order in a government gazette on Monday indicating the review will be extended by up to 90 days, which would delay a final decision by Treasurer Wayne Swan, and hold up a vote by Rio Tinto's shareholders.

Rio had aimed to complete the deal by July.

(Reporting by Sonali Paul)