Australia duo Steve Smith and David Warner have stood down as captain and vice-captain for the remainder of the third Test against South Africa.

Smith admitted that Australia's players planned to alter the ball during day three of the third Test in Cape Town.

Television footage showed opening batsman Cameron Bancroft take what he said was yellow tape out of his trouser pocket before rubbing the ball.

Smith confirmed that Bancroft's actions were planned by the "leadership group" of players in the Australia team during the lunch break.

"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," Australia CEO James Sutherland said in a statement.

"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."

Tim Paine will be captain for the rest of the match, which is into its fourth day, although Smith and Warner will continue to play.