Fair Australia has responded to allegations that prominent Voice to Parliament No campaigner, Warren Mundine, encouraged violence towards Yes advocates in a social media post.

Controversy sparked after Mr Mundine shared an image referencing a video posted online by former boxing world champion and his second cousin, Anthony Mundine, challenging Yes23 director Thomas Mayo to a fight.

Earlier this week, Anthony Mundine said Mr Mayo must be "taught a lesson" for breaking tribal law.

It is unclear what actions of Mayo's Mundine was referring to.

"He's broken tribal law and there's consequences. Us men have got to stand up," Anthony Mundine said in the video post.

"I'm gonna challenge him into the ring. Let's go man, we can get it on.

"I want to beat him up real good because he needs to be taught a lesson. Don't break our law."

The former fighter also loosely questioned Mayo's cultural heritage, claiming the Yes campaigner was actually a 'Mayor' only with ties to the Torre Strait Islands and not Aboriginal land.

Anthony Mundine has previously taken to his social media in opposition to the Voice, declaring the proposal was an effort to to end Indigenous sovereignty and instil a "new world order".

On Wednesday, Warren Mundine shared a photo of an article written about the challenge to his own Twitter/X, writing "I want to see that!!!" followed by a boxing glove emoji.

Yes campaign the Uluru Dialogue, headed by Uluru Statement from the Heart architects Professor Megan David and Pat Anderson, said Mundine's follow up was an "abhorrent" encouragement of violence.

The group said the message was a "leap" up from the no campaigns alleged encouragement for volunteers "to stoke confusion and fear" tactics in the lead up to the referendum.

Uluru Dialogue said no campaign messaging is in contrast to Noel Pearson's advocacy for love and inclusion after he spoke at the National Press Club on Wednesday.

Mr Mundine had addressed the club a day earlier.

"While Yes leader Noel Pearson spoke yesterday in the National Press Club of uniting Australians in love of country for a more positive future, No leader Warren Mundine publicly endorsed threats of violence against other Yes spokespeople," Uluru Dialogue said in a statement.

"We call on the Australian people to look past the deception, misinformation and violence, and focus on what we all stand to gain, the nation we can become, through a Yes vote on 14 October."

Yes23 declined to provide a comment to National Indigenous Times.

In their own statement issued Thursday, no campaign body Fair Australia, chaired by Mr Mundine, said it was "obvious to any fair minded Australian that Mr Mundine's tweet was light-hearted".

Fair Australia also took a swipe at the Yes campaign.

"The Uluru Dialogue is lying when they claim to be campaigning for unity, this just isn't true. They know full well that they're the ones trying to divide Australians with the Voice of Division," Fair Australia said.

"It's obvious to any fair minded Australian that Mr Mundine's tweet was light-hearted, and that he's the one campaigning to keep the country united.

"The hypocrisy of the Yes campaign is laid bare when their claims are measured against the violence and aggression seen from them at our rallies and the examples of appalling Yes volunteer behaviour, including the Yes23 spitter."

Earlier this month, a video surfaced of a woman in Yes23 t-shirt spitting at a person understood to be a no supporter.

Australians will vote in the Voice referendum on October 14.