STEVE Smith and David Warner most likely face one-year bans, with the 2019 World Cup and Ashes campaigns also in the balance.

As Smith's claim that the ball-tampering scandal was a one-off mistake was challenged in South Africa, Shane Warne dubbed the scam "un-Australian".

"At the end of the day, the captain decided to take a decision to cheat on the field," Warne said.

Australia’s highest profile players’ career are at a crossroad.
Australia’s highest profile players’ career are at a crossroad.

And Cricket Australia bosses have acknowledged that the disgraced captain and vice-captain, the alleged key ball tampering conspirators, must be sidelined for at least six months, according to insiders.

But with only a one-day series in England in June and a two-Test series against Pakistan over the winter - a ban also taking in next summer's series against India is more likely.

Such is the level of public anger that the pair's participation in next year's World Cup campaign in the UK and the following Ashes series is also at risk, sources say.

Darren Lehmann's head coach position was untenable, well-placed sources said, while young batsman Cameron Bancroft, who was put up to the tampering, was expected to face a lesser penalty to Smith and Warner.

Cricket Australia investigators landed in Cape Town late on Monday (AEST) and were expected to spend the next 24 hours exploring the level of involvement of all members of the touring party in the cheating scam.

They will report to CA chief executive James Sutherland, who also flew to South Africa on Monday night to determine penalties, which could come as soon as Wednesday morning.

Dark history: ball tampering in cricket.
Dark history: ball tampering in cricket.

Smith, who remained in Cape Town with fiancee Dani Willis ahead of his grilling, has already been suspended and misses the fourth Test in Johannesburg, which starts on Friday.

Warner and Bancroft also faced bans from the match.

But several other senior players, including bowlers Mitch Starc, Josh Hazlewood and Nathan Lyon have tried to distance themselves from involvement in the scandal after Smith said the decision to tamper with the ball was made by the "leadership group".

The bowlers, angry at being linked to the "meeting" in the Cape Town dressing room, have sent messages to management and sponsors to plead their innocence.

With the depth of ill-feeling among the Australian cricket community continuing to grow, CA is said to be well aware it needs to take significant action.

A 12-month playing ban, imposed now, would be enough for both Smith and Warner to potentially return to the Australian team in times for next year's World Cup campaign in the UK, and the Ashes series which follows it.

Steve Smith is facing a player revolt.
Steve Smith is facing a player revolt.

If the pair's CA and Indian Premier League deals are dumped they also face losing a combined $4 million, with individual sponsorships, worth millions of dollars more, in the balance.

Cricket Australia has contacted its major sponsors to assue them the matter is being dealt with the utmost urgency and seriousness.

Some, including the Commonwealth Bank, have demanded strong action.

"We are disappointed about the events that have emerged from the third Test in South Africa and have asked for a full explanation from Cricket Australia following the conclusion of its investigation into this affair," a bank spokesperson said.

No sponsors, of the players or Cricket Australia, have withdrawn their support yet, choosing to wait for the outcome of the investigation.

Life bans are available to CA as a penalty for the players under its code of behaviour, but that remains an unlikely outcome.

Sutherland is expected to hand down penalties in Johannesburg before the fourth Test.

"We know Australians want answers and we will keep you updated on our findings and next steps, as a matter of urgency," Mr Sutherland said.

Cricket Australia chairman David Peever said the board fully supported the actions taken by Mr Sutherland.

"We understand that everyone wants answers, but we must follow our due diligence before any further decisions are made," Mr Peever said.