A review is being held into whether there has been a conflict of interest because of the personal relationship between Ms Courtney and DPIPWE head Dr John Whittington.

Community and Public Sector Union secretary Tom Lynch has written to Premier Will Hodgman asking that both decisions made - as well as those not proceeded with - be investigated and that DPIPWE staff be authorised to speak to investigators without fear of any repercussions.

“We understand there are a number of DPIPWE staff who have information that could be relevant to the investigation,” Mr Lynch said in the letter.

“We understand this information goes specifically to decisions that were taken by the Minister for Primary Industries and/or the Secretary of DPIPWE to accept certain recommendations and also, and perhaps more importantly, decisions not to accept certain recommendations.”

Mr Lynch said there could be a conflict of interest in decisions that were not proceeded with by either Ms Courtney or Dr Whittington.

“DPIPWE has responsibilities for land management including issues around development on crown land and environmental protection and these are areas where a separation between political and community interests are critical,” he said.

In the letter he said: “Staff are concerned that the investigation you have ordered will only look at those decisions that were made to proceed with certain matters and therefore ignore decisions that were made not to proceed or where recommendations were dismissed.

“Any investigation should fully review all these matters and not just be limited to decisions to proceed.

“A conflict of interest can exist in both circumstances.”

Mr Lynch said DPIPWE staff were not in a position to provide “frank advice” or evidence to an investigator unless they were instructed by a person in authority.

“No investigation can claim to have fully considered the relevant evidence unless DPIPWE staff are encouraged, supported and protected to disclose what they know,” he said.

“There are some very stressed DPIPWE staff out there and encouraging, supporting and protecting them to give evidence would be in their best interests and in the public interest.”

A government spokesperson said all decisions were “included in the scope of the investigation” and that DPIPWE staff had been given authorisation to speak.

She also said the review was being done independently from the Premier, his office and his staff.