A proposed joint venture between BHP Billiton (BHP) and Rio Tinto (RTP) to merge their Western Australian iron ore mining businesses won't lessen competition between the two to market the raw material, Australia's Trade Minister, Simon Crean, said Wednesday.

The proposed merger would see the two companies, which dominate exports from the Pilbara region in Northwest Australia, share iron ore export facilities in a bid to gain efficiencies and get costs down, he said.

"They will still operate as separate marketing arms, they will therefore be competitors and so there won't be any lessening of competition," Crean told reporters.

"When the details of the proposal emerges there will be acceptance of that," he added.

China has raised concerns about an Australian export monopoly emerging as a result of the proposal.

-By Ray Brindal, Dow Jones Newswires; 612-6208-0902; ray.brindal@dowjones.com