Australia's competition regulator said that BHP Billiton Ltd has completed submissions allowing the regulator to start a review of BHP's planned bid for rival Rio Tinto Ltd. But it did not give a timeframe for the review.

The Australian Competition and Consumer Commission in a statement said that it will invite comment from other participants in the mining industry, their customers and other interested parties.

The bid has sparked opposition from steel companies around the world over concerns that a merged entity would have too much control over pricing of raw materials such as iron ore.

Last week BHP filed with the European Commission for clearance to take over Rio and said recently that it expected that review to go to a second phase. EC has set a deadline of July 4th 2008 for consideration of the deal.

Analysts said that the most contentious area is likely to be iron ore, since the combined firm would control around a third of seaborne trade in the raw material for making steel.