The competition watchdog has again pushed back the date by which it was to release its findings on the proposed merger of Rio Tinto Ltd's and BHP Billiton Ltd's iron ore operations in Western Australia.

Mr Graeme Samuel chairman of Australian Competition and Consumer Commission said late last month that the ACCC would issue its final determination on July 22.

But on the ACCC's website the ACCC said the proposed date had been suspended at the request of the joint venture parties to allow them to make additional submissions to the ACCC.

It said that "A new proposed date for the announcement of the ACCC's findings will be advised in due course.”

The ACCC is examining whether or not the deal would be a breach of the Trade Practices Act. It is understood Chinese steel makers are among parties that have made submissions to the ACCC on the planned mega-merger.

BlueScope Steel Ltd has also made submissions, saying it was opposed to the transaction.

European regulators are expected to be the main hurdle to the tie-up proceeding.

(Sourced from AAP)