Two media heavyweights have reached a deadlock in an online dispute, with a lack of witnesses willing to verify either version of events.

TV3's political editor Duncan Garner and media veteran and political adviser Brian Edwards yesterday repeated that they stood by their opposing versions of an incident between Garner and MP Chris Carter before an Air New Zealand flight 11 months ago.

Garner and Edwards began a bitter online debate in Edwards' blog, after accusations by Edwards that Garner's reporting had turned into a personal campaign against Mr Carter, who was recently demoted from holding his foreign affairs portfolio for overspending on his ministerial credit card.

The incident, which involved a brief exchange between Mr Carter and Garner in the Koru Club, which continued as Garner boarded the plane, was witnessed by Labour chief whip Darren Hughes who was with Mr Carter in the Koru Club and Dame Margaret Bazley who was on the plane.

Both have declined to comment.

Edwards, who worked in media training and advice with former Prime Minister Helen Clark for 13 years, claims that "several" sources told him what had happened.

"I heard this story from a variety of sources and I then rang Mr Carter and asked him whether the story was correct and he said that it was."

He claims that as Garner boarded the plane, where Mr Carter was already seated, he poked the MP and said: "I am going to f****** get you, Carter. If it takes me to Christmas I am going to f****** destroy you."

But Garner said yesterday he swore "On my kids' lives" that he never touched the MP.

"I've been around here for 15 years," he said.

"I'll f****** smash them on the TV but I will not f****** touch them physically. I know the rules.

"I stand by my recollection of it. He called me a c*** and then it went from there."

Garner said Mr Carter provoked the exchange in the Koru Club. Then, when he boarded the plane and asked Mr Carter "what was that about?", Mr Carter told him to "F*** off".

Garner replied: "If you want a f****** war, you'll get one."

He said he did not usually get involved in online debates but he believed Edwards was writing whatever Mr Carter told him and he wanted to set the record straight.

"On this one I thought 'I'm going to get involved because Edwards is bulls******* through his teeth'.

"These guys misconstrued it right from the start. They are a dribbling joke."

Chris Carter declined to comment again yesterday.

"I think that it's Dr Edwards' blog - I know I'm half of the subject of it but I think you have to discuss it with him."

He denied encouraging Edwards to stand up for him.

"I'm not in his ear and I think you have to ask him that question ... I'm not saying anything on the issue."

Asked whether Edwards' version of events was what Mr Carter said happened, he said:

"I'm not going to make any comment at all."