The Corrections Department has written to TV3 regarding a journalist who it said visited Clayton Weatherston in jail without authorisation.
The department said reporter Alison Horwood breached prison security to speak to Weatherston, who is awaiting sentence after being found guilty last month of murdering former girlfriend Sophie Elliott.
Horwood did not get chief executive Barry Matthews' approval, which was needed for all media interviews with prisoners, the department said last week.
TV3 said they had not yet received the letter.
However, TV3 director of news and current affairs Mark Jennings has previously said he understood Ms Horwood had filled out the required form correctly.
An interview that Horwood conducted with Weatherston's parents, Roger and Yuleen, was broadcast on 60 Minutes on Monday.
During the item, Horwood spoke of visiting Weatherston in prison.
