Pat Cummins has flatly denied Usman Khawaja's claims that the entire team was implicated in the 2018 sandpaper scandal as "complete and utter nonsense" and "100% wrong" in a defiant appearance at a press conference a week after the allegations came to light.

Appearing before dozens of reporters and cameras at Cricket NSW's headquarters in Sydney and fielding questions for more than an hour, Cummins refuted the allegations aired in his former teammate's book, Sabr, and said he had no knowledge of the ball tampering plot in South Africa.

Australia's captain at the time Steve Smith, vice-captain David Warner and opener Cameron Bancroft were handed long suspensions by Cricket Australia after the governing body's short investigation into the incident.

Khawaja alleges in his memoir that more than just the three banned players were aware of the team's ball-tampering plans, and that sandpaper was also used on the ball during the preceding Test. The former Australia batter has called for "all" of the team to take collective responsibility.

Cummins said Khawaja was a friend to him, but "friends aren't casual with each other's lives and reputations", adding he had been "grappling" over recent days as to whether their relationship was irrevocably harmed.

He said Khawaja was "100% wrong" with his claim that the whole team knew sandpaper was going out on the field, maintaining "I did not know that was happening" and "did not see anything on the ball" at the time.

"He says that I and others were architects of a scheme to ball tamper with sandpaper. That's complete and utter nonsense," Cummins said.

"I was genuinely shocked this week when I found out Usman admitted he told Cam [Bancroft] to be careful when using sandpaper. That's not Usman that I know. It's not the Usman that has been part of the team that's helped rebuild the Australian cricket culture over the last eight years.

"Usman is a friend, but friends aren't casual with each other's lives and reputations. In his book he's been casual with my life and the lives of many others and, I think, Australian cricket."

Cummins added that there was "no masterplan around using illegal methods".

"I think that's maybe something that hasn't been spoken about enough," he said. "People assume you have gone from very legal methods to suddenly taking sandpaper and then must have been some huge master plan. That is not the case. There's no grand plan, there's no bowlers saying, 'this is what must happen'."

Cummins did concede that the 2018 Australian men's team had a "win-at-all cost mentality" and an "ugly underbelly" which he said he had tried to eradicate in his past six years as captain.

"I thought that the way we acted on the field was quite abrasive. I didn't like the way we spoke to umpires, the opposition," he said.

"I think there was a bit of an arrogance and a bit of an ugliness at times that didn't sit well with me as a young guy. And now I'm captain, I have spent a lot of time making sure that that's not the case with this current Aussie team."

Cummins said he had texted with Khawaja briefly since his memoir was released on Tuesday but didn't delve into the nature of their correspondence. He said "some of" the claims in his memoir were "probably true … and they are his accounts of what happened", but added there were "a few big leaps here where he's being vague".

"Perhaps there was conversations with Cameron Bancroft around taking sandpaper out and how to do it," he said. "That doesn't mean that everyone in that dressing room knew what was going on.

"If we are talking about how [the players] were sanctioned, my personal opinion was it was way too heavy-handed … But to then extrapolate that out into everyone else knew … that's very different to what I think was injustice."

He also rejected Khawaja's testimony in Sabr that he wasn't picked as Australian team captain after Smith and Warner stepped down because of racism. Khawaja wrote he was "flabbergasted" when Tim Paine was named interim captain, and alleged Cricket Australia wasn't ready for a "brown Australian cricket captain".

"I think of all the things I've read this week, I think that's actually the most serious," Cummins said. "I agree with Uzzy on a lot of things, but … him saying that if you're Australian captain you have to be a certain skin colour, I couldn't disagree with that statement any more."

Asked whether he was considering taking legal action for the claims aired in the book, Cummins said he had received advice this week that some of the allegations he made were "probably defamatory" but said "I won't be doing that".

"You've got to move on," he said. "It's been eight years … You got to draw the line at some point. I won't be doing that."