Cricket South Africa confirmed the news in the build-up to the home series versus England.
Without disclosing any of the three names, CSA informed that about 50 COVID-19 RTPCR tests were conducted on players and support staff before those who resulted negative were allowed to enter the bio-bubble created for the series.
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"One player has returned a positive test result and two players were considered close contacts based on the risk assessment undertaken by the medical team," said CSA in a media release.
"All three players have been placed in immediate isolation in Cape Town as part of the COVID-19 protocols. While all players are asymptomatic, CSA's medical team will monitor them to ensure their health and well-being," the board added.
There hasn't been any replacement named but CSA confirmed that two new players will join the squad in order to make up the numbers for the intra-squad warm-ups that will help with the pre-series preparations this weekend.
"At this stage, none of these players will be replaced for the tour, but two replacement players will be included into the squad for the purposes of the inter-squad practice matches that will be played on Saturday, 21 November," the board said.
The England team have already reached South Africa to finish off with their quarantine period before the on-field action.
The tour kickstarts with the first of three T20Is in Cape Town and also features three ICC Super League ODIs, which count towards 2023 World Cup qualification process.
(Inputs from PTI)