TOKYO (Nikkei)--The Japan Fair Trade Commission has begun its antitrust review of a plan by BHP Billiton Ltd. (BHP, BHP.AU) and Rio Tinto Ltd. (RIO.AU) to merge their Australian iron ore mining operations, commission Secretary-General Takahide Matsuyama told a news conference Wednesday, The Nikkei reported in its Thursday morning edition. The commission will decide by July 16 whether to allow the two Anglo-Australian mining giants to proceed with the combination, or to conduct a second screening. BHP and Rio supply about 60% of Japan's iron ore. Steelmakers warn that the merger will hinder free competition in the iron ore trade. "The commission with take a comprehensive view of the state of competition and new entry and examine the problem points," Matsuyama said. (END) Dow Jones Newswires June 23, 2010 10:42 ET (14:42 GMT)