Steve Smith, David Warner and Cameron Bancroft have been handed punishments that do not fit the crime of ball tampering, according to Australia great Shane Warne.

The trio were handed international and domestic suspensions by Cricket Australia on Wednesday after being found guilty of trying to alter the condition of the ball against South Africa in Cape Town.

Smith and Bancroft admitted the offence at a media conference after the third day's play at Newlands, with the former subsequently stood down as captain for the remainder of the Test.

A Cricket Australia investigation was launched and the pair – along with vice-captain Warner – were subject to hefty sanctions.

Smith and Warner were banned for 12 months, while Bancroft will not be eligible to play for nine months, with all three having the right to appeal.

Australia's actions on the pitch have brought condemnation from across the globe, but Warne believes the authorities have gone over the top with the punishments they have handed out.

"To hear that the Australian cricket team had been involved in premeditated cheating is something that is embarrassing," Warne wrote for News Ltd.

"But the jump to hysteria is something that has elevated the offence beyond what they actually did, and maybe we're at a point where the punishment just might not fit the crime.

"The hysteria has gone worldwide … But what are the players guilty of? Cheating via ball tampering and bringing the game into disrepute.

"Their opposing captain in this series, South Africa's Faf du Plessis, has been charged with ball-tampering twice, and opening bowler Vernon Philander once.

"Then there's the idea of premeditated cheating. But are there levels of ball tampering, or is it just ball tampering? Is putting a mint in your pocket so you can shine a ball on the field premeditated cheating, or just ball tampering? What about putting sunscreen on the ball? You either ball tamper or you don't.

"For that reason, I don't think the punishment is fitting the crime."

While the three players were punished, coach Darren Lehmann was not sanctioned, much to the surprise of many. However, Warne is confident his former team-mate has not been protected by the Australian authorities.

"Darren Lehmann has been cleared of knowing what went on too, which has surprised plenty, but that's all part of the hysteria," Warne added.

"It's easy to say 'as if Boof didn't know'. But all we can go [on] is what we've been told. This is too big a deal, too big a story, there is too much at stake for the game and (CA chief executive) James Sutherland to lose, not (to) tell the truth.

"We are all struggling to believe what he said, that it was just the three players who knew what was happening, that the coach had to know.

"We all saw him on the walkie talkie. But you have to take James at his word."