North Melbourne have sacked Tarryn Thomas after he was suspended for 18 games by the AFL for threatening a woman and other misconduct.

Thomas was investigated by the AFL's integrity unit after the latest in a string of allegations were made in January.

The AFL found Thomas guilty of various acts of misconduct, including threatening a woman via direct messages multiple times.

"There is no excuse for the behaviour or the hurt he caused a young woman," the AFL's general counsel Stephen Meade said in a statement on Thursday.

"The fact that Tarryn chose to engage in behaviour over direct messages that was, and is, clearly inappropriate, even while he was undertaking education and being counselled for previous breaches, contributed to the length of suspension imposed."

Thomas, who has not trained with his club since January 17, was due to fall off-contract at the end of the upcoming season.

But North terminated the 23-year-old's contract, effective immediately, with club president Sonja Hood saying Thomas is "out of chances".

"I'm feeling a range of emotions - frustration, anger, disappointment - but overall, sadness," Hood wrote in a letter to members.

"This wasn't a decision based on emotion - it was driven by incontrovertible, uncontested facts - but I want to be clear it wasn't, and isn't, easy."

Last year, amid separate allegations of inappropriate behaviour towards women, the club put Thomas through a respect and responsibility education program.

The AFL on Thursday said Thomas engaged in misconduct while he was undertaking the program.

Thomas returned to the club in May via the Kangaroos' VFL ranks before earning an AFL recall and playing the last 12 games of the season.

In July last year, he avoided a criminal conviction from a court appearance for threatening to distribute intimate videos of his former partner.

The initial charge was downgraded to using a carriage service to harass someone and he was granted a diversion and ordered to pay $1000 to charity.

"Tarryn came back to the club midway through last year pledging to be better," Hood wrote.

"We are all bitterly disappointed that he has relapsed. And he is now out of chances."

Hood praised the woman at the centre of the latest allegations for "her bravery and the dignity with which she has handled herself".

North will continue to make available medical and mental health support to Thomas, as will the AFL Players Association.

North's football manager Todd Viney said Thomas would not be paid the remainder of his contract.

"I can't read into Tarryn's mind," Viney told reporters.

"But certainly from my point of view, there's two Tarryns - there's the one that we see play the game and there's one there that has some troubles dealing with relationship issues.

"If it's not a wake up call, I don't know what will be."

The AFL said for Thomas to return to playing at any level, he must undertake - and pay for - another behavioural change program.

That program would need to be approved by the AFL, which would need assurances of Thomas's progress before clearing any return to the sport.

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