Rugby: All Blacks halfback Aaron Smith says tryst cost him haka role

All Blacks halfback Aaron Smith has revealed that his toilet tryst cost him the honour of leading New Zealand's pre-match haka,

The 29-year-old made headlines during the 2016 Rugby Championship after he was caught entering a disabled toilet cubicle with a woman, who wasn't his partner, at Christchurch Airport on September 18.

The All Blacks were in South Africa when the news broke, and he was sent home as a result.

In a new book called The Jersey, by British journalist Peter Bills, Smith speaks about the incident which led to him stepping down from the role.

"I was one of the first to say, 'I should not be doing it', and that is what happened," Smith says.

"It's a part of the mana, isn't it? You lose mana when you do things like that. TJ Perenara took over, and I was happy for him to do that because of the mana I had lost from what I had done."

TJ Perenara has since been leading the haka for New Zealand.

All Blacks mental skills coach Gilbert Enoka said the consequences for his actions really took a toll on the Highlanders star.

"What Aaron did was so severe for himself personally that it shattered him hugely," Enoka said.

"He needs to think why he screwed up. It was like a tide that crept up.

"You think you are indestructible and above different things. But suddenly you come crashing down in a huge way."

The Jersey will be released on August 14.