Faf du Plessis’s pleas of innocence over ball tampering have been met with a withering assessment from the MCC World Cricket Committee, with the body’s head of cricket, John Stephenson, saying the South Africa captain’s actions “flagrantly contravened the law”.

Du Plessis is seeking to have the guilty verdict handed down to him overturned on appeal. He was fined 100% of his match fee by the International Cricket Council under its code of conduct after television footage emerged from the second Test against Australia in Hobart last month showing him applying sugared saliva from a mint in his mouth to the ball in an attempt to aid swing.

The 32-year-old said he had done nothing wrong, claiming there is a difference between ball tampering and ball shining, and has since lodged an appeal against the verdict with the ICC that will be heard by an independent judicial commissioner, Michael Beloff QC, on 19 December.

With ball shining an integral part of the game, players including Alastair Cook have called for greater clarity as to what is and is not acceptable given that taking sweets or sugary drinks on to the field of play is allowed. Other artificial substances such as sun cream or lip salve may also find their way on to the ball.

The MCC World Cricket Committee, which is an independent panel that can propose changes to the laws of cricket, considered this topic during a two-day meeting in Mumbai and decided the rules relating to ball tampering – which state it is acceptable to “polish the ball provided no artificial substance is used” – do not need changing.

The panel, chaired by the former England captain Mike Brearely, also concluded no set guidelines are required, stating that “to try to be too prescriptive by listing banned substances would be counterproductive”.

Asked what advice he would now give to players in light of this decision, Stephenson said: “My advice would be not to contravene the law, which is very clear. I was part of that [Du Plessis] hearing and in my opinion what he did flagrantly contravened the laws. He put his finger straight on to the mint, straight on to the ball and was caught on camera. It was a clear case of ball tampering.

“There will be grey areas and we hope cameras don’t follow players but if you are not breaking the laws you don’t have anything to worry about. We are not trying to stop people shining the ball, we want it to swing. But it was obvious to me, you couldn’t argue that it went straight on to the mint and straight into the ball.”

Brearley said: “If you speed, you will probably get away with it but sometimes you are caught, and if you are caught flagrantly doing something, you deserve to face the penalty, which seems to me what happened with Faf du Plessis.