Steve Smith and David Warner have decided to step down as captain and vice captain of the Australia cricket team for the remainder of the ongoing third Test against South Africa in Cape Town.

Wicket-keeper Tim Paine has been announced as the interim skipper.

"Following discussions with Steve Smith and David Warner they have agreed to stand down as Captain and Vice-Captain respectively for the remainder of this Test match," Cricket Australia (CA) CEO James Sutherland was quoted as saying by cricket.com.au.

“This Test match needs to proceed, and in the interim we will continue to investigate this matter with the urgency that it demands. As I said earlier today, Cricket Australia and Australian cricket fans expect certain standards of conduct from cricketers representing our country, and on this occasion these standards have not been met," he added.

On Saturday, CA had said that Smith was to remain captain while they investigate a ball-tampering scandal during the third Test against South Africa that has plunged the game into crisis.

There had been calls for Smith to step down or be sacked over the premeditated plan hatched during the lunch break on Saturday's third day in Newlands, after the captain admitted being the mastermind.

Australia Prime Minister Malcolm Turnbull weighed in on the incident today, saying it "beggars belief" that role models such as Australian cricketers were "engaged in cheating like this". Chief executive James Sutherland said Cricket Australia were "extremely disappointed and shocked" but added that the governing body wanted to get a clearer picture of the facts before making any decisions.

CA's head of integrity Iain Roy and head of team performance Pat Howard were flying to South Africa to conduct the investigation. Television footage showed Smith's teammate Cameron Bancroft, 25, taking a yellow object out of his pocket while fielding in the post-lunch session and appearing to rub it on the ball. He was later charged with attempting to change the condition of the ball.

Sutherland said he had not spoken to Smith but stressed repeatedly he was unhappy about the incident. "I have very strong and clear views about the responsibility of the Australian cricket team to play the game in the right spirit," he added. "And I don't think anyone will be under any illusions as to what I think about this." Smith, 28, has said he would not quit, adding: "I still think I'm the right person for the job."

The CA chief said Australian cricket fans had "every reason to wake up and not be proud of the team". "This is a very sad day for Australian cricket. I'm not happy about this at all ... And I feel like Australian cricket fans feel right now."

There was widespread disbelief in Australia as the news hit the headlines on Sunday morning, with the significance of the incident evident when Turnbull added his voice to the chorus of displeasure. Turnbull told reporters he had spoken to CA chairman David Peever, who reassured him that the body "will be responding decisively, as they should".

"The whole nation, who holds those who wear the baggy green up on a pedestal -- about as high as you can get in Australia, certainly higher than any politician that's for sure -- this is a shocking disappointment," he said. "It's wrong and I look forward to Cricket Australia taking decisive action soon."

Government agency the Australian Sports Commission called for Smith and others involved or aware of the plan "to be stood down immediately" by CA as it completes the investigation. Smith's predecessor Michael Clarke said he was feeling "pretty emotional" after the revelations.

"I can't believe if the leadership group has made a decision to do this, that they have gone and got the young kid (Bancroft) who is playing his eighth test match to do that," Clarke told broadcaster Channel Nine.

Clarke said he felt sorry for Smith, but added that the tampering was "blatant cheating" and "disgraceful". Players' body the Australian Cricketers Association said it supported the investigation. "It seems serious errors of judgement have been committed... Cricket is a sport synonymous with the highest standards of behaviour," the ACA said in a statement.