The player is ruled out for South Africa's fall fixtures.
South Africa front-rower Wessels has received a ban of nine matches for making contact with opponent Josh Murphy's genitals during the Blue Bulls' URC win over the Irish province.
The incident happened in the early stages of the close contest against Connacht on Friday, with opposing player Josh Murphy being shown a temporary dismissal after responding aggressively by hitting the South African on the head.
Following the Connacht player complained to the match official, the event was checked by the television match official, who found no definitive proof.
The Bulls player remained on the pitch until he was replaced in the later stages of the game.
Although the United Rugby Championship announced that Murphy's 20-minute red card was withdrawn by a governing body, the Springbok was found to have breached law 9.27, which states:
"A player must not engage in actions that is contrary to the spirit of good sportsmanship. This includes touching, pulling or squeezing the genitals."
The panel were satisfied that the event met the level for dismissal and warranted a three-month ban, the minimum ban under World Rugby rules for such an infringement.
Nonetheless, Wessels' ban was reduced by 21 days because of his good conduct during the hearing and his good record.
The forward and the Pretoria-based team have the right to challenge the decision, but currently, the suspension will rule the young player out of the South African national team's autumn Tests against Japan, France, Italy and the Irish team.
He will also miss the Bulls' league matches against Glasgow, the Emirates Lions and the Sharks, as well as European cup games with Bègles and Northampton.
Wessels has earned 10 caps for South Africa and was part of their tri-nations champion team over the summer.
Murphy, meanwhile, is available to face the Irish rivals in Saturday's domestic clash after being cleared.
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