Australia's competition watchdog has announced on Monday the deadline on June 22 to decide on the proposed $16 billion ($A132.8 billion) iron ore joint venture between two iron ore miners.

The Australian Competition and Consumer commission has been due to give a decision on the proposed merger between Rio Tinto and BHP Billiton last month but was pushed back to seek more information frpm the miners without setting a time frame for the decision.

According to the competition regulator's website, the “proposed” date was set for July 22 to declare its findings on the said merger.

Both miners have agreed to join their iron ore operations in Western Australia to help offset the impact of the Federal Government's proposed resources super profts tax. The joint venture is expected to generate more than $10 billions in savings.

It was revealed that ACCC had planned to give its verdict in February, however, concerns were raised in March from different parties on the joint venture by the second and third largest iron miners worldwide.

Steelmakers, car makers, regulators in China and Japan, and the European Commission have expressed their dismay that the competition will hamper and may control more than two-thirds of the global iron iroe trading.

The decision of the European Commission may be scheduled later this year.

Under the joint venture deal, BHP will pay Rio Tinto $US5.8 billion ($A6.7 billion) on every five per cent stake to even their holdings in the 50-50 venture, valuing it at $US116 billion.

Combining both iron ore mines and their related infrastructure in Wetsern Australia's Pilbara region will be crucial for the companies, as they will generate more than $11.8 billion in savings.

Amids plans of the Federal Government to pursue its resources super profits tax, both companies will push through with the iron ore tie-up.

"We're fully committed to the joint venture," BHP spokeswoman Amanda Buckley said last month.

Shares of BHP Billiton and Rio Tinto peaked at 1.78 per cent to $39.83 and 1.9 per cent to $72.20 respectively.