Speaking at the Monday night dinner of the NSW Minerals Council's annual Hunter Valley conference, Mr Barilaro said that in a case of "extraordinary over-reach" the IPC wanted the United Wambo open-cut mine near Singleton to be accountable for the "Scope 3" greenhouse gas emissions of its customers in other countries.

Under the internationally recognised system of greenhouse gas emissions, Scope 1 emissions in a coalmine are those directly emitted when the coal is mined.

Scope 2 emissions are those incurred in running the mine, such those from the electricity or diesel used at the mine.

Scope 3 emissions - which are by far the largest - are those emitted when the coal is burnt, and are attributed to the business (and therefore the country) that is using the coal.

Speaking with the Newcastle Herald after his speech, Mr Barilaro said forcing an Australian export mine to account for Scope 3 emissions was a clear case of "double counting" because those emissions accrued overseas.

He confirmed he was unhappy with chair of the commission, former NSW chief scientist Dr Mary O'Kane, who is scheduled to speak at the conference today.

NSW Minerals Council chief executive Stephen Galilee also criticised the commission, saying "we support the deputy premier's determination to ensure the NSW government, and not an un-elected body, sets policy in the way that projects are assessed and emissions accounted for in that process".

In his speech, Mr Barilaro said the planning system in NSW was a "black box", with an un-elected and "so-called" independent body turning out decisions that were "out of kilter" with the objectives of the government.

He said there was no clearer example of this than the "appalling" statement posted on its website at 9.30pm on Friday in relation to United Wambo.

"Seeing the IPC reference Scope 3 as a genuine reason to reject or influence mining decisions, resource decisions, planning decisions is something we as a government must react to immediately and urgently," Mr Barilaro said to applause from his 500-strong mining audience.

United Wambo involves a joint venture between Glencore's United mine and Peabody's Wambo in which the Wambo open-cut would continue and a new open-cut developed above the adjoining United underground mine, which closed in 2010.

In a statement Mr Barilaro said was posted on its website at 9.30pm on Friday, the commission says the panel deliberating on the United Wambo mine was "considering a condition" on the mine's approval that meant the company "must" use its best endeavours" to ensure its coal was exported only to countries that had signed the Paris Agreement or had what the Planning Secretary considered to be "similar policies".

"The purpose of the Export Management Plan is to ensure that all practicable measures are adopted by the Applicant to minimise greenhouse gas emissions identified as Scope 3 emissions in the EIS [Environmental Impact Statement],' the statement says.

The statement said its proposal followed "comments" received over the Rocky Hill and Wallarah 2 proposals.

Mr Barilaro told the Herald that Rocky Hill was rejected on its merits, including its proximity to the town of Gloucester, but the presiding judge had "noted" Scope 3 emissions.

"We should not be responsible for Scope 3 emissions," Mr Barilaro said.

He said there were "question marks" about the Rocky Hill decision that meant it should not have become a precedent but it "looked like it had".

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