A day after South Africa took an unassailable 2-0 lead in the test series in Australia by winning in Hobart, footage emerged showing Du Plessis with a white lolly in his mouth, licking his finger before shining the ball.
Applying an artificial substance to alter the condition of the ball contravenes the ICC's code of conduct.
"The ICC has been alerted to the footage and is currently reviewing the incident from the perspective of it being a possible breach of the ICC Code of Conduct," an ICC spokesman said in a statement.
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The world governing body has five days from the close of play on Tuesday to charge the South Africa skipper after the match referee's report did not mention the incident.
In 2013, Du Plessis was fined 50 percent of his match fee for ball tampering in the second test against Pakistan.
He was caught on camera rubbing the ball against a zip on his pocket on the third day of the match in Dubai, leading umpires Ian Gould and Rod Tucker to penalise South Africa five runs and change the ball. Du Plessis did not contest the charge.
(Reporting by Sudipto Ganguly in Mumbai; Editing by Ken Ferris)
