The Independent Commission Against Corruption has confirmed it has commenced a preliminary investigation into whether Newcastle MP Tim Crakanthorp breached the ministerial code of conduct.
Premier Chris Minns referred Mr Crakanthorp to ICAC on August 1 for what he described as a "significant breach of the ministerial code" for failing to disclose "substantial" private family holdings near the proposed Hunter Park development at Broadmeadow.
Following his sacking, Mr Crakanthorp told Parliament he "unfortunately omitted" a property owned by his wife, Laura, from his initial ministerial disclosure and became aware of a conflict of interest involving his in-laws' Broadmeadow properties some time after lodging that first disclosure.
Mr Crakanthorp's wife or her family are not accused of any wrongdoing.
Mr Minns said at the time that the former Minister for the Hunter would be dumped from the Labor party if ICAC launched a formal investigation.
In documents tabled to parliament on Wednesday, ICAC chief commissioner John Hatzistergos has confirmed the body was "conducting a preliminary investigation into whether Mr Crakanthorp substantially breached the ministerial code of conduct".
Mr Crakanthorp declined to comment about the development.
The ICAC and the Cabinet Office have refused an Upper House request to release all documents relating to disclosures made by Mr Crakanthorp under the ministerial code, any rulings made by the premier, and advice relating to potential breaches.
Mr Hatzistergos said publishing such documents "has the potential to prejudice the commission's investigation and would not therefore be in the public interest".
A Cabinet Office review conducted following Mr Crakanthorp's sacking found there were no major issues with the decision-making and governance processes surrounding the development, and that planning should continue to provide certainty for the community.
The review recommended the pause on NSW Government work on the Hunter Park precinct planning should be lifted to reduce delays and provide certainty to stakeholders and the community.
The review was conducted by the Cabinet Office and engaged Chris Wilson, an independent planning expert, to provide advice on land use planning matters in the report.