Australia's competition regulator said Tuesday it had launched an informal review of BHP Billiton's proposed joint iron ore venture with Rio Tinto to seek comment on the controversial deal.

The Anglo-Australia mining giants on Saturday signed a binding agreement to combine their vast Western Australia iron ore operations, a tie-up expected to result in 10 billion US dollars in savings.

The deal is opposed by Asian and European steel makers, which have called for an investigation into whether it would be anti-competitive.

"Comments are invited from interested parties regarding the proposed joint venture," the Australian Competition and Consumer Commission (ACCC) said.

Findings were expected to be released in February 2010, it added.

The two miners said Saturday they believed European Union authorities were already investigating the deal, which is expected to be complete by the second half of 2010.

Rio and BHP will evenly split their Western Australian iron ore assets and liabilities, and have said the venture will deliver "substantial synergies" aimed at producing more iron ore at lower cost.

Announced after the collapse of a 19.5-billion-dollar bid for Rio by Chinese state-owned firm Chinalco, the deal also follows BHP's dropping of a hostile takeover bid for Rio amid the global economic turmoil in November 2008.

The ACCC gave BHP's earlier takeover bid the green light, finding it would be unlikely to substantially lessen competition, despite the fact it would combine two of the world's three largest suppliers of seaborne iron ore.

Analysts do not expect the ACCC to oppose the iron ore venture, and see European regulatory approval as its greatest hurdle.