Rugby Australia's chairman complained today that the "dark forces" of online criticism had made life miserable for the organisation's first female CEO, who has stepped down after a spell of intense pressure.

Paul McLean expressed his "own personal disappointment" at the way Raelene Castle had been treated before she resigned late on Thursday, saying she believed the RA board no longer wanted her in the role.

McLean - a former fly-half who won dozens of caps for the Wallabies - paid tribute to the trailblazing Kiwi, saying a lesser person would have thrown in the towel long ago.

Castle had, he said, been attacked in a "vicious and vitriolic way", particularly on social media, by "silent forces, dark forces".

"She shared some of that with me, which was, you know, I found quite abhorrent."

Castle was the first woman to lead any of Australia's major men's sports bodies. Her departure ends a turbulent reign marked by a series of crises and escalating financial problems.

Ex-Wallaby captain McLean, who is due to step down on 31 July, said he would adopt the role of executive chairman "for a very short period" while the hunt begins for Castle's replacement.

Castle quit only two days after telling reporters she was determined to see RA through the coronavirus shutdown which has left it battling for survival.

Hours later, an open letter from 11 former Wallabies captains demanding leadership change was published in the media, heaping further pressure on her.

McLean said the letter had no bearing on the board's move on Castle, and added that most of its signatories' views on how to fix the sport carried little weight given they were no longer involved in it.

"It's great that people want to put their hand up and get involved but they need to be a part of the process," he said.

"Let's be clear here, it's a very small collective of people who've been involved in the game of late. The significance of that group is probably people that aren't on the list."

Two-time World Cup-winner John Eales was among a separate group of ex-captains who criticised the letter, while Michael Lynagh asked to be removed as a signatory.

McLean said that by December this year, two-thirds of Rugby Australia's top positions will have changed in a year.

Rugby Australia has laid off most of its staff and slashed players' pay by 60 percent as it grapples with the coronavirus crisis, which looks set to torpedo much of this year's Wallabies schedule.

The Super Rugby season, which involves four Australian teams and others from South Africa, New Zealand, Argentina and Japan, was suspended mid-March at the end of the seventh round.

A prolonged shutdown would be disastrous, with RA projecting a A$120 million (€70m) hit to its finances if unable to schedule any matches in 2020 due to Covid-19.