The announcment of the trading halt before market open on Friday said it would remain in place "pending the release of an announcement by the company''.
Reports overnight from London and Beijing said the $US20 billion deal between Rio and Chinalco had fallen apart.
The Sydney Morning Herald reported on Friday that Rio had "informally notified Chinalco over the past day or so it will be withdrawing its recommendation (to shareholders to support the deal) and would be replacing it with a $15 bililon rights issue''.
Rio Tinto turned to Chinalco in February to help repair a balance sheet weighed down by $US38.7 billion ($A48.36 billion) in debt. A payment of $US8.9 billion is due in October.
Under the deal, Chinalco would invest $US12.3 billion in joint investments in aluminum, copper and ore mining with Rio Tinto, and spend $US7.2 billion on convertible bonds in the company.
If redeemed for shares, the bonds would almost double Chinalco's existing 9.3 per cent stake in Rio Tinto Group to 18 per cent.
In mid-May, the debt-laden miner said it was still commited to the deal, in response to a request from the Australian Securities Exchange to try to explain a plunge in the company's share price.
That share drop interrupted a rally in the stock since February, making the convertible bond that Chinalco was to buy less attractive for its shareholders.
The Foreign Investment Review Board was due to make a decision on the deal, based on national interest, by the middle of this month.
If Rio Tinto calls the deal off, it will likely be required to pay Chinalco a $US195 million dollar break fee.
Rio Tinto shares closed 7 per cent lower at 2,720 pence on the London Stock Exchange overnight.
In Australia, they closed last night at $66.90.
The trading halt remains in place at this stage until trading opens on Tuesday, June 9, or when the statement is made.
