Wessels will be unavailable for the Springboks' autumn internationals.
Springbok prop Wessels faces a suspension of nine games for making contact with opponent Josh Murphy's private parts during the Blue Bulls' United Rugby Championship win over Connacht.
The incident happened in the early stages of the close contest in Galway on Friday, with opposing player Murphy receiving a temporary dismissal after reacting angrily by striking Wessels on the head area.
After the Connacht player reported the incident to the match official, the situation was reviewed by the television match official, who determined no conclusive video evidence.
The Bulls player remained on the pitch until he was substituted in the later stages of the match.
Although the United Rugby Championship confirmed that Murphy's temporary sending-off was overturned by a disciplinary panel, Wessels was deemed to have violated law 9.27, which specifies:
"Any athlete should not engage in actions that is against the spirit of good sportsmanship. This includes grabbing, twisting or compressing the genitals."
Disciplinary officials were satisfied that the contact met the level for dismissal and warranted a 12-week suspension, the minimum suspension under World Rugby rules for such an infringement.
However, the player's ban was reduced by three weeks because of his cooperative behavior during the proceedings and his good record.
The forward and the Pretoria-based team are entitled to challenge the decision, but as it stands, the suspension will rule the 24-year-old out of the South African national team's autumn Tests against the Brave Blossoms, Les Bleus, Italy and Ireland.
Wessels will additionally be absent for the his club's league matches against Warriors, the Emirates Lions and the Cell C Sharks, as well as Investec Champions Cup games with Bordeaux and Northampton.
Wessels has earned ten international appearances for South Africa and was included in their Rugby Championship-winning squad during the recent tournament.
The Connacht player, meanwhile, is eligible to face the Irish rivals in this weekend's inter-provincial derby after being exonerated.
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