Israel Folau has questioned Rugby Australia's integrity and is demanding to know how and why confidential details of his code of conduct hearing were leaked.
The sacked Wallabies star reportedly sent an email to all 10 RA directors seeking an explanation as to how details of his sworn testimony were published in News Corp last week.
"This is blatantly unfair. As you know, the tribunal hearing must be closed and private, and Rugby Australia was obliged to keep all information confidential," Folau wrote in his damning letter sent to RA chief executive Raelene Castle, chairman Cameron Clyne and eight others.
"I would like to know why Rugby Australia has not managed to maintain the integrity of its processes and ensure that information was kept private and confidential."
Folau also took exception with the way he thought he has been portrayed in the media, accusing the governing body of providing unfair and misleading information.
"For example, I am not 'sick of rugby' and whoever told the media that I am is telling lies," he wrote.
"Another example is the way the media has been told that that your expectations were made clear to me by Ms Castle. We all know that that is far from the truth.
"It makes me sad that these things have apparently been told to the media by someone at Rugby Australia. If you are not the source, why has no-one come out to set the record straight?"
Folau's letter to the board of directors was emailed just two days after his lawyers filed an application with the Fair Work Commission to deal with his unlawful termination dispute.
He is seeking $5 million in lost earnings, plus "substantial" damages.
The independent tribunal that heard Folau's code of conduct case found the dual international guilty of a "high-level" breach for posting bible passages on his social media accounts that RA deemed to be anti-gay.
"I decided not to 'appeal' the panel's finding because I wasn't confident you would treat me fairly if I did. This week's media shows that my instincts were right," Folau said after opting instead to take the matter directly to the Fair Work Commission.
Rugby Australia on Saturday night rejected Folau's claims of lacking integrity in the bitter dispute that has divided Australia.
"While we accept that a PR firm has been engaged to coordinate a media campaign to promote the legal action taken against Rugby Australia, we are disappointed that this campaign is impacting on the work done by the thousands of volunteers who are delivering great experiences for the rugby community and also that it has taken the focus away from a crucial Australian Super Rugby derby, being played by Israel's former team tonight," the statement read.
"Rugby Australia has acted with complete professionalism and integrity at all times through the process in which Mr Folau was found by an independent three- member tribunal panel to have made multiple, serious breaches of the Professional Players Code of Conduct.
"While we will continue to respond to any legal action as required and will continue to defend the values that underpin our game and the work done by the hard working volunteers, we will not engage in a running media commentary."