Rugby Australia (RA) chairman Paul McLean has staunchly backed departed chief executive Raelene Castle, who he says was subjected to "abhorrent" bullying from "faceless people" during her time in the job.

Key points: Paul Mclean praised Raelene Castle's commitment to the job in the face of "unwarranted criticism"

Paul Mclean praised Raelene Castle's commitment to the job in the face of "unwarranted criticism" McLean dismissed the impact of a letter from former captains of the Wallabies

McLean dismissed the impact of a letter from former captains of the Wallabies Former Wallabies captain Stephen Moore called for major changes to be made to Rugby Australia's governance

Castle announced last night she was stepping down as RA chief executive, a post she had held since late 2017, explaining she no longer felt she had the support of the governing body's board.

Her decision to quit came three days after a no-confidence letter — signed by a number of ex-Wallabies captains — sent to RA was made public, calling for an overhaul of its leadership.

McLean, himself a retired Wallabies captain, will assume the role of executive chairman until a replacement for Castle is appointed.

He said Castle, who was named RA chief executive in late 2017, did not deserve the criticism she received during her tenure.

"Criticism is easy, being cynical is easy, but decision making is tough," McLean said.

"She was able to do that and do that with some clarity.

"She would run through broken glass to get things done, and she has done that."

Castle's handling of the Israel Folau settlement and her rejection of Fox Sports's initial broadcast deal beyond this season were a source of criticism from some quarters, while the code's financial plight has been laid bare by the coronavirus pandemic.

Radio broadcaster Alan Jones was a long-time critic but McLean said it was not the media scrutiny that stung Castle the most.

"It's the silent forces, the dark forces that upset me most," he said.

"It's the people who didn't ask, didn't know the facts or just one of those faceless people out there, that was the damaging thing from her perspective and she shared some of that with me, which I found quite abhorrent.

"[If not for the] unwarranted criticism and, in fact, bullying, I think it might have been a different scenario."

McLean insisted most people in Castle's position would "have thrown in the towel ages ago" but that inevitably her departure had become the clear way forward.

He dismissed the impact of the former captains' letter — which included the signatures of the likes of Nick Farr-Jones, George Gregan, Phil Kearns and Stephen Moore — saying they could easily align with recovery efforts that were already underway.

"I've had numerous conversations with Nick Farr-Jones and, let's be clear here, it's a very small collective of [those] people who have been involved in the game of late," McLean said.

"The significance of that group is probably the people that aren't on the list."

Rugby Australia needs 'major changes'

Moore said he acknowledged the contribution made by Castle during her time at RA.

But he said there needed to be leadership change at RA for it to recover from its poor financial position, as well as for the Wallabies and Australia's Super Rugby teams to improve their on-field performances.

"These problems are deep-seated, they have been going on for quite some time," Moore told ABC News Breakfast.

"A lot of the players involved in the last week or so have been contributing in different ways over a long period of time but we haven't been able to make the changes that are needed.

"This is a major, urgent matter. Rugby in Australia is deteriorating at a rapid rate and no one is happy about that. We need to do something really major to turn things around."

There has been much speculation that the initial push to remove Castle from her role was to pave the way for Kearns to take her place.

Kearns was a candidate for chief executive when Castle was appointed.

Stephen Moore says Australian rugby needs significant change at the governance level. ( AAP: Dave Hunt )

Moore, who played 129 Tests for the Wallabies, said the letter sent to RA was not designed to propel Kearns into the chief executive position, nor to promote Nick Farr-Jones as a potential RA chairman.

"That is not correct, that is certainly not the intention here," he said.

"There will be a process to appoint a CEO, that would be the appropriate avenue but it is far too early to comment on any of that.

"At the moment we are united as a group together and we want to try to promote the required changes.

"These changes are not minor. They are very, very major changes to the governance of the game in Australia and the way the game is structured and delivered right from grassroots through to the professional game."

Moore confirmed there had been further correspondence between some of the former captains and RA, amid rumours a second letter had been issued to the organisation.

"There's been correspondence between Rugby Australia and also the group of Wallaby captains so that is ongoing. That has been really constructive," he said.

"We look forward to that continuing. We want to provide solutions and there are solutions that have been provided.

"So I would really ask anyone who's commenting publicly to try and find all the facts that they can before making their assumptions and we are working as hard as we can to promote these changes internally."

'The game is bigger than any one individual'

Castle, who has vast sporting administrative experience in her native New Zealand and Australia, issued a statement exclusively to ABC's 7.30 program last night, highlighting her reasons for stepping down as RA chief executive.

"I love rugby on every level and I will always love the code and the people I have had the honour of working with since I took this role," she said.

"I made it clear to the board that I would stand up and take the flak and do everything possible to serve everyone's best interests.

"In the last couple of hours, it has been made clear to me that the board believes my no longer being the CEO would help give them the clear air they believe they need.

"The game is bigger than any one individual — so this evening I told the chair [Paul McLean] that I would resign from the role.

"I will do whatever is needed to ensure an orderly handover. I wish the code and everyone who loves rugby nothing but the best and I would like to thank the people I work with and the broader rugby community for their enormous support."

Dave Rennie was appointed by Castle to begin as Wallabies coach this year. ( AAP/SNPA: David Rowland )

The fallout from her decision to leave RA may impact on new Wallabies coach Dave Rennie, who has previously indicated he might not take up the role if Castle was no longer chief executive.

But Castle, speaking before making the announcement she was leaving RA, said she expected New Zealander Rennie would take up his position as Wallabies coach.

"He will come here regardless of where I sit," she said.

AAP/ABC