The warning came a day after Wallsend MP Sonia Hornery used parliamentary privilege last month to name council boss Jeremy Bath as the author of the nasty letter-writing campaign.

Ms Hornery called for Mr Bath to be sacked, declaring the council boss had "shamefully abused" his $550,000 a year job funded by Newcastle ratepayers.

In response, council's executive manager legal and governance Emily Kolatchew issued a confidential memo to councillors informing them that the code of conduct investigation into any links between Mr Bath and the letters was "not to be publicly disclosed".

Ms Kolatchew acknowledged "media reports and discussions in public forums" and "reminded" councillors that they were bound by council's code of conduct to keep any information about the investigation confidential.

She then went on to say that the purpose of the memo was to provide them with an update about the investigation, which is being handled by an investigator from workplace relations firm Pinnacle Integrity.

"The code of conduct matter is under investigation," the memo reads.

"The time taken to conclude the investigation is a matter for the investigator and will be dependent on a variety of factors including the availability of interviewees and the steps the investigator is required to take to comply with the procedure for administration of the code of conduct, including procedural fairness."

The November 22 memo is stamped with the word confidential across each page.

In July, the council unanimously voted in favour of the investigation after Local Government Minister Ron Hoenig publicly said he planned to contact lord mayor Nuatali Nelmes requesting the matter be examined.

Mr Bath has denied any involvement in the misleading letter-writing campaign, which has followed his career progression for more than a decade, attacking his critics and extolling his employers' virtues.

Dozens of letters have been submitted to publications throughout NSW under the name Scott Neylon, a close friend of Mr Bath's who has lived in Japan for decades.

As previously reported, they are designed to mislead and deceive by twisting facts and distorting reality.

Mr Neylon has sidestepped questions about how he has such an in-depth knowledge of Newcastle politics and has refused to explain the inconsistencies and inaccuracies in the correspondence over the past decade.

Ms Kolatchew said her role was to coordinate complaints within council, but Pinnacle Integrity was managing the investigation and she would have no further updates until the matter was completed.

"On 13 September 2023, the Pinnacle Integrity completed the preliminary assessment and determined to investigate the matter," the memo reads.

"On 20 September 2023, councillors received a memo. In this memo, councillors were advised that they would be next updated at the conclusion of the investigation."

Under the code of conduct, the councillors may resolve to take disciplinary action against Mr Bath under his employment contract if he is found to have been in breach.

The code also says the council is not obliged to adopt the investigator's recommendations, but it must state in its resolution why it chose not to do so and notify the Office of Local Government of its reasons.

The OLG has the power to review "at any time" the consideration of a matter under a council's code of conduct.