Mumbai: BHP Billiton's proposed $160 billion (Australian $194billion) hostile bid to take over Rio Tinto hit another regulatory bump after the European Commission (EC) placed its review on hold and sought more information from BHP.

EC, which was expected to finalise its review of BHP's proposed takeover of Rio Tinto and hand down its decision on 9 December, has now announced that the process has been stalled for want of more information.

The news comes amidst mayhem in the commodity markets that prompted a shifting in investor focus away from mining and energy stocks.

The EC move, coming after comments by Chinalco chairman Xiao Yaqing that left open the possibility of the Chinese aluminium giant selling its 9 per cent stake in Rio under BHP's current offer, will likely hammer Rio shares further.

The EC review is now likely to extend well into the time around Christmas. That would make a decision rather difficult this year, say analysts.

The international steel industry and the Australian Competition and Consumer Commission have also voiced concern over the deal on the ground that a BHP-Rio combine would have too much control over iron ore prices.

The unexpected development has fuelled concerns that the regulatory body will strike down BHP's bid, as it has already expressed  "serious concerns'' about the competition issues raised by the proposed mega-merger.

BHP said it was working to comply with the EC's demands ans said the suspension was a normal part of the phase two process. ''BHP is still confident the regulatory pre-conditions for the offer can be satisfied."

A merger between BHP Billiton, the world's third-biggest producer of iron ore, and Rio Tinto would create an entity producing over one-third of the world's iron ore.

While BHP got provisional clearance from US regulators, the Australian Competition and Consumer Commission last month expressed concerns of a price hike for Australian steelmakers following a BHP-Rio merger.

The ACCC has called for submissions by the end of this week and is expected to announce its final decision by 1 October.