Former Australian captain Steve Smith has shed further light on his role in the ball-tampering scandal in South Africa, admitting he did not "want to know about it" when the plan was being hatched.

Key points: Steve Smith says his role in the ball-tampering incident was a "leadership failure"

Steve Smith says his role in the ball-tampering incident was a "leadership failure" Smith admitted he had struggled at times to come to terms with his 12-month ban

Smith admitted he had struggled at times to come to terms with his 12-month ban He will be available for selection for next year's World Cup and Ashes series

Smith, who was banned for 12 months for his role in the incident, said he let himself down by not trying to stop "something from happening" when he saw David Warner and Cameron Bancroft in a discussion in the dressing room in Cape Town.

"I walked past something and had the opportunity to stop it, and I didn't do it," Smith said in his first media appearance since arriving back in Australia in March.

"That was my leadership failure. It was the potential for something to happen and it went on and happened out in the field and I had the opportunity to stop it at that point."

When asked what he said as the discussion was taking place, Smith replied: "I don't want to know anything about it."

Then-vice-captain Warner was also banned for 12 months and Cameron Bancroft was given a nine-month sanction.

"That [discussion in the change room] was my chance where I could have stopped something from happening," Smith said.

"That's something I've learned over the last nine months, that every decision you make can have a negative outlook.

"If things go pear-shaped, what's it going to look like? If things go well, how does that look?

"Now it's about learning and almost slowing your thinking down and ensuring that you make the right decisions more often than not."

Steve Smith has been allowed to play Sydney grade cricket while suspended. ( AAP: Joel Carrett )

Smith, who has been allowed to play Sydney grade cricket during his suspension, said he had struggled at times in the fallout from what happened in Cape Town.

"I'm going OK. I've had tough days," he said.

"I've had my ups and downs. I've been really fortunate to have a close group around me that helped me get through those difficult times.

"There has been some dark days where I haven't wanted to get out of bed and things like that.

"But I've had a close group of people around me that have helped me know that it's OK.

"I've made a mistake and it was a big mistake, and from now on I'm trying to move on from that and improve as a person."

Smith aiming for World Cup, Ashes selection

Smith and Warner will be eligible for international selection in March, meaning they could both earn selection for Australia's squad for the World Cup to be hosted by England.

Smith dismissed the suggestion there had been a breakdown in his friendship with Warner, saying relations between the two were "fine".

Steve Smith (right) and David Warner will available to play for Australia in March. ( Reuters: Rogan Ward )

Smith said he was focused on making both the World Cup and Ashes squads next year but would not reveal if he still had the ambition to captain Australia in the future.

"The next three months, it's just about preparing as well as I can to hopefully be a part of the World Cup and the Ashes," he said.

"I think Tim Paine has done an exceptional job and Aaron Finch taking over the one-day side, he's had a tough start to that with the performances of the team, I guess.

"But if I get back and play under them, I'll do everything I can to help them out and help Australia have success."

Smith has come under fire this week for his role in a TV advertisement for a telecommunications company, which refers to the ball-tampering incident.

The advertisement is aligned with the Gotcha4Life Foundation, established by media personality Gus Worland to help create awareness about mental health issues.

Smith said he took part in the advertisement to help the foundation, rather than for financial reasons.

"I'm getting paid, but I'm also putting forward funds towards the Gotcha4Life sessions," he said.

"Gus and I haven't sat down and exactly figured out where it's all going, but in the new year we'll do that and figure out where I can put towards this organisation to help create that awareness around mental health."