The fallout of Australia's ball-tampering in the third-test against South Africa has been quick and severe, with Steve Smith stripped of the captaincy, Bancroft fined 75% of his match fee and questions posed over Darren Lehmann's tenure as coach. 

However, details are just beginning to emerge about how Bancroft was caught, with de Villiers telling RSN Radio that he alerted South African broadcaster SuperSport about the unusual movement of the ball, which ultimately caught the Aussies out.

"I said earlier on, that if they could get reverse swing in the 27th, 28th and 29th overs then they're doing something different to what everyone else does," he said.

"We actually said to our camera men, go out and have a look boys. They're using something."

Supersport tracked Australia's cricketers - following the ball closely from wicket-keeper Tim Paine to the bowlers - for over an hour and a half, before eventually uncovering Bancroft producing an item from his pocket, which he then used to tamper the ball.

"It's impossible for the ball to get altered like that on cricket wickets that we knew there was grass on," he continued.

"Australian teams getting swing before the 30th over, they had to be doing something."