James O'Connor© Bradley Kanaris/Getty Images

Former Wallabies full-back and Triple M host Greg Martin has returned serve at James O'Connor, warning the outgoing Queensland Reds utility, "I know where a lot of the skeletons are buried, mate".

Martin branded O'Connor an "immature t--t" and a "little young punk" earlier in the week after O'Connor was released from the final year of his contract by the Reds due to "personal issues".

The 25-year-old hit back through a 1500-word Facebook post, in which he slammed Martin's treatment of high-profile sports stars and claimed Martin was bullying and "had no interest in the truth".

Martin refused to back down, though, and hit back with another verbal spray on radio on Friday morning, reminding the youngster that the stoush started with a war of words on twitter two weeks ago.

"He's got his lawyer to right a 1500-word (Facebook response). It's the first time he's written more than 140 characters apart from apologising to a club who's bum-rushed him out the door," Martin said on Triple M.

"Bullying is when you start a Twitter war where you don't want someone to fire back - two weeks ago he had a crack at me.

"James, I warn you, when you get these words, I know where a lot of the skeletons are buried, mate.

"I know what's going on (in) the world and I know what you've done and we could tell a lot more so let's finish this right here and right now, mate."

The Reds cited O'Connor's "personal matters" as the reason for letting him out his contract, his release coming after a one-season return from overseas exile following a series of off-field problems encountered playing Super Rugby and for the national team.

Will Genia had to step in between teammates James O'Connor and Adam Thomson during an argument at half-time #dramas pic.twitter.com/GSyZni3xzY

— Jamie Pandaram (@JamiePandaram) May 22, 2015

"Greg did not say these comments while I was present, he offered me no chance to respond and frankly from the position I stand he does not care," O'Connor wrote. "He has no interest in the truth; he has no interest in finding the real story.

"Greg's interest is his own opinion and making his own headlines, with no consideration to whom he drags through the mud. "I am the first to recognise that my previous behaviour was not one of an upstanding individual but, like all people, I wish to learn from my mistakes and look to improve myself.

"Greg's comment on 'everyone else growing up, except for James O'Connor' implies that I have no recognition of the consequences of my previous actions.

"I find it ironic that the man accusing me of being immature then proceeded to call me an 'immature tw--t', and 'a little punk' on live radio. A childish insult at best, from a 50-year-old father."

O'Connor said Martin should have more empathy for his plight when not privy to the reasons behind his release from the Reds.

"A recent headline that sticks out for me is the much-publicised story of another prominent athlete's own personal issues," O'Connor wrote. "However, the key difference in this, was that this person received support from not only his peers but also Australian media and was used as a tool to highlight the importance of recognition of mental illness.

"I do not need to answer the speculation of a man that obviously has little empathy toward fellow athletes.

"Instead of support, Greg felt it necessary to question my character when for all he knows my mental state could be extremely unstable.

"The fact is the man is trivialising mental health issues by making such comments when he knows nothing about the circumstances surrounding my release."