"I had discussions with the match officials, I've been charged with attempting to change the condition of the ball," Bancroft, 25, said after play in Cape Town. "We had a discussion during the [lunch] break and I saw an opportunity to use some tape, get some granules from the rough patches on the wickets and change the condition, it didn't work, the umpires didn't change the ball. I was sighted on the screen and that resulted in me shoving it down my trousers."

The incident took place during the afternoon session and was picked up on by TV cameras. A small, yellow object was seen in Bancroft's hands after he had worked on the ball, and he was also captured taking it from his pocket and placing it down his trousers. The footage showed Bancroft rubbing the rough side of the ball, the opposite side to which he would usually be trying to shine on his trousers. He put the object down his pants apparently after being spoken to by the substitute Peter Handscomb, who had come on to the field after speaking to coach Darren Lehmann over walkie talkie. Lehmann seemed to speak to Handscomb after footage of Bancroft working on the ball was shown on the TV screens at the ground.

The umpires Nigel Llong and Richard Illingworth were then seen speaking with Bancroft, though they did not choose to change the ball or penalise the Australians five runs - the statutory on-field penalty for illegally changing the condition of the ball.

When Bancroft spoke to the umpires, he was shown holding a bigger, black cloth rather than the small yellow object he had earlier seemed to place down his trousers. Both South African and Australian commentators on the host broadcaster, SuperSport, said Bancroft's actions looked suspicious. "It is very suspicious. There is no doubt about that," Allan Border said at the time. "If you're caught doing the wrong thing, you've got to pay the penalty."

The former South Africa captain Graeme Smith said he was surprised the umpires had not changed the ball. "In my opinion I think he's tampered with the ball and used an object to do that," Smith said. "It does look like it's a bit of sandpaper. The footage doesn't look good. I'm quite amazed the umpires haven't done anything with the ball. The footage is quite damning.

"If it is proved that what has gone on in the footage is correct then some tough questions have to be asked of Steve Smith and Darren Lehmann. I think there is a lot of questions that need to be answered and Australia need to answer them. For me it's quite obvious that he's doing something with the ball and the umpires need to do something about it."

Shane Warne, meanwhile, said it was unlikely that Bancroft had acted alone, without the knowledge of his captain and coach. "You've got to own up and say what was it that you were hiding," Warne said. "You can't have that in the game. We've got to get to the bottom of it. The Aussies have to be honest and say 'this is how it happened'. I don't have any issue with anyone if they are sucking on a mint or chewing some gum, then that's just natural saliva.

"But if you use a foreign object and it tampers with the ball then that has to be seriously looked at. Let's get to the bottom of what it is and how did it happen. And it's not fair to nail Cameron Bancroft on it either. I don't think he would have made that decision by himself. We've got to get to the bottom of it. You know when you get caught you've got to own up and be honest. The Aussies have to be honest and say this is how it happened."

A contrite Steven Smith fronted the media after play. "The leadership group knew about it. We spoke about it at lunch," he said. "I am not proud of what's happened. It's not within the spirit of the game. My integrity, the team's integrity and the leadership group's integrity has come into question. It wont happen again.

"It was the leadership group's idea. Poor choice and we deeply regret our actions. The coaches weren't involved. It was purely the leadership group who came up with this. This is the first time it has happened under my leadership. We saw this game as such as an important game. We've seen the ball reversing through this series and this ball didn't seem like it was going to go. It's such poor actions. Deeply regrettable and wont happen again. I can promise you. I can promise you this is the first time it has happened.

"I am embarrassed. I know the boys in the shed are embarrassed as well. Being the leader, I am incredibly sorry. If we weren't caught, I would still regret it.

"I wont consider stepping down [from captaincy]. I still think I am the right person for the job. Today was a big mistake on my part and on the leadership group as well. I have to take control of the ship. This is something I am not proud of. It's something I hope I can learn from and come back from. I am embarrassed. It is a big error in judgement."

Australia's bowlers had been able to gain pronounced reverse swing on day three in Cape Town, though South Africa continued to build their second-innings lead. Questions about ball tampering have been raised throughout the series, where reverse swing has been a consistent theme.

Warner was highlighted for the bandages on his hand in Port Elizabeth, the result of numerous finger injuries suffered while batting in the past, and on day one at Newlands the fast bowler Pat Cummins was seen to tread on the ball, though the umpires did not view it as deliberate, and saw no reason to penalise the Australians or change the ball.