Documents released to NSW Parliament last month showed that Ms Berejiklian in 2017 requested the Australian Clay Target Association's application for a Wagga clubhouse grant be reassessed after its business case failed to show a net benefit to taxpayers.

Former Wagga MP Daryl Maguire had been heavily involved in campaigning for the clubhouse and had written to Ms Berejiklian, then NSW Treasurer and his secret romantic partner, in January 2016 to advocate for the grant.

Department of Regional NSW secretary Gary Barnes was questioned at a NSW Parliament budget estimates hearing on Monday morning about his prior correspondence with Ms Berejiklian's staff concerning the grant application.

Mr Barnes declined to answer multiple questions about the grant, claiming it was under "ongoing investigation" by the Independent Commission Against Corruption.

Labor MLC John Graham asked Mr Barnes about a letter from regional NSW executive director Chris Hanger to Infrastructure NSW chief executive Jim Betts in June 2017 seeking "review and consideration" for the Wagga grant "following a request by the Premier".

"What was the nature of the request from the Premier?" Mr Graham asked Mr Barnes at Monday's hearing.

"Mr Graham, unfortunately, as you are no doubt aware, Operation Keppel is ongoing and the grant is something that the ICAC are looking at, and therefore it would be inappropriate for me to talk about this matter today," Mr Barnes replied.

Mr Barnes is the second NSW public servant this month to refuse to answer questions about the grant on the basis of claims that ICAC is investigating that matter.

Department of Premier and Cabinet deputy secretary Kate Boyd told a parliamentary hearing on August 18 that it would not be appropriate for her to "comment on the substance of matters that are clearly currently under investigation by the ICAC" in response to questions about the grant.

An ICAC spokesperson said on Monday that the commission does not confirm or deny if an investigation is taking place.

The Copland Street clubhouse, which includes The Range function centre, was ultimately successful in gaining the $5.5 million grant from the Restart NSW program and the building was opened in 2018.

Earlier this month, Ms Berejiklian said any suggestions she had a conflict of interest in the grant process were "absolutely ridiculous".

"All proper processes were followed and that's all I'll say on the matter," she said.

During Monday's hearing, Mr Graham continued to push Mr Barnes for answers and said he could not understand why he could not talk about a now-public document while appearing before Parliament.

"The advice I have received is that it would be inappropriate for me to engage in a conversation about the specifics about this particular project," Mr Barnes said.

According to testimony before ICAC last year, Mr Maguire later had a small commercial interest in the Wagga clay target grant as a company he secretly controlled, G8wayInternational, obtained a commission via importing furniture for the centre.

Documents released to Parliament show that the Wagga clay target centre grant's business case was accepted after its benefit-to-cost ratio to taxpayers was revised from 0.88 to 1.10 in the project's favour.

This new benefit estimate was largely based on increasing the projected interstate visitors to the centre, a projection that was developed with the help of staff from Deputy Premier John Barilaro's office.

Mr Graham asked Mr Barnes if raising the benefit/cost ratio was "crucial to the progress of this project; it effectively moved it from a red light to a green light?"

"Without that upgrade, that documents from your agency say was requested by the Premier, this project would not have proceeded with Infrastructure NSW funding, is that correct?" Mr Graham asked.

Mr Barnes said he could respond only in general terms.

"Infrastructure NSW is responsible for making sure that the full criteria for Restart NSW that restart projects have, and one of them is economic viability, are met," Mr Barnes said.

"That is checked by Treasury officials before a recommendation is made to the minister responsible for Restart, and that is the Treasurer.

"My understanding around Restart projects is that the convention is that a benefit/cost ratio of 1.0 is preferred, I'm sure that it's not legislated but it has become customary practice."

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