The editor-in-chief of The Australian, Chris Mitchell, has sent a letter of demand to journalism academic Julie Posetti, confirming he will pursue her for defamation over a series of tweets .

Mitchell is understood to be seeking an apology for Posetti’s tweets at an academic conference last week at which a former News Limited journalist criticised Mitchell for controlling the coverage of human-induced climate change.

It is understood that Mitchell is not pursuing damages but is demanding a fulsome apology over the comments by journalist Asa Wahlquist, who described writing about climate change at The Australian as “torture” and “debilitating”.

The letter also contains an offer from Mitchell for Posetti to visit the offices of The Australian and observe the editorial process of the paper, he has also offered for her to sit in on editorial meetings.

Mitchell has also offered to attend mediation with Posetti.

The topic has been hotly debated on twitter since last Friday, with a special site #twitdef canvassing hundreds of mostly negative comments from Posetti’s supporters.

Posetti had tweeted that Mitchell as editor-in-chief had prescribed her coverage of climate change in the paper. But Mitchell denied this to Crikey, describing the assertion as a “lie”.

As Crikey reported on Friday,  former senior News Limited journalist and respected rural affairs journalist for more than 20 years, Asa Wahlquist mounted an off-the-cuff defence of environmental reporting on a panel at a journalism educators conference at UTS in Sydney last week, explaining the difficulties of having stories published about climate change because of the attitude of and pressure from senior editors at the paper.

Her comments were quickly reported on Twitter, prompting editor-in-chief Chris Mitchell to threaten legal action against the author of the tweets and anyone else who published the “lie”.

Mitchell told Crikey that “any reading of The Oz’s editorials on climate change would make it clear that for several years the paper has accepted man-made climate change as fact”.

It has supported market mechanisms to reduce carbon output for the best part of a decade,” he said. “What people do not like is that I publish people such as Bjorn Lomborg. I will continue to do so, but would suggest my environment writer, Graham Lloyd, who is a passionate environmentalist, gets a very good run in the paper.”

Wahlquist, the long-time science and rural affairs writer for The Australian, accused Mitchell of controlling coverage of climate change because he believes those who subscribe to the “eco-fascist line” that humans have induced climate change are “aiming to destroy everything he loves and values”.

Wahlquist subsequently backed away from some of her comments, but days later a tape of the conference surfaced that seemed to support Posetti’s paraphrasing.

Julie Posetti is standing by her Twitter coverage. The journalism academic told Crikey earlier this week that she has reviewed the tape and, “while I cannot comment on the truth or otherwise of what she said, I stand by the accuracy of the quote I attributed to Asa Wahlquist”.

Crikey has the full recording that can be downloaded here and here (MP3 – approx. 2mb). Watching the panel session on environmental journalism, Posetti tweeted on Thursday:

It was absolutely excruciating. It was torture’: Asa Wahlquist on fleeing The Australian after being stymied in covering #climate’

Wahlquist: ‘Chris Mitchell (Oz Ed) goes down the Eco-Fascist line’ on #climatechange.’ I left because I just couldn’t do it anymore”

Wahlquist: ‘In the lead up to the election the Ed in Chief was increasingly telling me what to write.’ It was prescriptive.

The tape records Wahlquist making each of the statements about the paper and Mitchell. What’s more, says Posetti: “I consider the quote to have been in relation to a matter of significant public interest concerning journalism and politics and was appropriately the subject of discussion in my tweet.”