Top broadcaster Carol Hirschfeld has accused Rachel Smalley of inverse sexism for criticising the appointment of her old 3News colleague John Campbell.
Smalley called the decision "extremely disappointing" as it had come at the expense of Checkpoint host Mary Wilson.
"We're introducing yet another white male broadcaster to prime time, at the expense of a strong, capable, experienced female interviewer," she wrote.
"Let's look at who's hosting the two primetime slots in this country, breakfast and drive. We've got Mike Hosking, Paul Henry, and Guyon Espiner and Susie Ferguson in a co-host role on National Radio. In drive, you have Larry Williams, Duncan Garner and now John Campbell."
Hirschfeld, Radio NZ's head of content, said: "I think Rachel's thesis seems strange and somewhat misguided. She seems to be suggesting it would be better if Mary Wilson stayed on the air to satisfy some kind of false gender balance argument rather than actually relishing a change and taking on what is a powerful news role.
"And I think that apart from it being a little patronising, I think Rachel is putting forward a kind of inverse sexism argument, strangely enough."
Asked if she was surprised by Smalley's comments, Hirschfeld said: "Not really, I mean Rachel likes to, when there is a major media event, she likes to get involved and I'm sure she felt taking a sort of contrarian view like this, which would be provocative in certain circles, was worth the risk."
She rebutted Smalley's claim that white male broadcasters "shape our day", "direct our news agenda" and "influence our opinions and perspectives".
"I'm presuming that must be the case at Newstalk ZB because certainly it's not the case at Radio NZ, nor has it been at other places I've worked including Maori TV, TV3 and TVNZ.
"News agendas are shaped by teams of journalists and I am pleased to note that right now, where I work, and all the places I've worked in the past, there's a very healthy gender mix," Hirshfeld said.
Other media personalities joined in the debate on Twitter. Pip Keane, the former executive producer of Campbell Live, said: "Poor Rachel Smalley has sour grapes," noting that she was once Campbell's back-up presenter - and hadn't yet congratulated him on the new role.
Former Campbell Live reporter Ali Ikram tweeted that "the only thing u need no about JC's "perspective" is the day the show was canned he was reporting on an otara woman working 3 jobs 2 get by".
He added: "JC's move to RNZ does not change the gender balance of the media. One extra woman on prime time TV and another in senior management at RNZ."
Radio NZ's Morning Report host Susie Ferguson retweeted a message saying Smalley had raised "a good point".
Radio New Zealand chief executive Paul Thompson tweeted that Smalley had "raised an important issue and that should be respected as we debate it".
He told the Weekend Herald Wilson had been promoted to a leadership role and "Mary will actually be John's boss".
Campbell was taken off air when Campbell Live was cancelled in May. Heather du Plessis-Allan and Duncan Garner take over the 7.30pm timeslot on Monday with TV3's new show Story.