The review started last week and notices calling for public submissions were made on Wednesday with the closing date for those submissions July 9.

ACCC is especially seeking views on the potential impact on prices from the Shell-BG deal and on whether Shell and BG compete closely.

It also wants to know "how easy it would be for existing competitors to expand and/or new competitors to enter the market and constrain the merged entity post-merger".

While the review is separate from the ACCC's ongoing inquiry into the east coast gas market it is also seeking insights into the "gas market competition" aspects of the Shell-BG deal.

The ACCC officially does not have the power to enforce conditions on this proposed takeover but will challenge merger and acquisition deals through the courts if it has any competitive concerns.

The informal review process consequently has the potential to shape takeover deals. The ACCC could make its views known on competition concerns involving the Shell-BG deal through a "statement of issues" announcement on September 3.

More information about making a submission can be found under the "mergers register" section of the ACCC website.

Meanwhile, the Shell-BG deal won regulatory approval in the US this week with Shell CEO Ben van Beurden telling the St Petersburg International Economic Forum that the takeover deal, expected to be completed in early 2016, was on track.