England have returned two "unconfirmed" positive coronavirus tests after the abandonment of their first ODI against South Africa.
Sunday's game in Paarl had been called off 30 minutes before it was due to begin at 8am UK time, with two members of staff at the team hotel having tested positive for Covid-19.
England's touring party underwent an additional round of tests on Saturday evening and are now self-isolating in their hotel rooms while they wait for further medical advice.
A joint statement from the England and Wales Cricket Board and Cricket South Africa read: "The decision was taken after two hotel staff members testing positive for COVID-19. As a precaution, the England players and management underwent an additional round of PCR tests on Saturday evening.
"Following the test results, two members of the England touring party have returned unconfirmed positive tests for COVID-19. The players and management are now self-isolating in their rooms until further advice from the medical teams."
The ECB and CSA also said a decision on the final two matches of the series will be made once the results of the tests are ratified independently by medical experts.
Monday's ODI in Cape Town has since been postponed, although the games could still take place on Tuesday and Wednesday ahead of England's planned departure on Thursday.
The ODI series was due to start in Cape Town in Friday but was postponed after a South Africa player tested positive for coronavirus - the Proteas were tested again on Friday evening and all returned negative Covid results.
Ashley Giles, England's managing director of men's cricket, said: "We regret that we are unable to play in today's ODI, but the welfare of the players and support staff is our primary concern and whilst we await the results of further tests the medical advice from both teams was that this game should not take place.
"We remain in constant dialogue with Cricket South Africa and will continue to work closely with them to determine how best to move forward."
South Africa's director of cricket, Graeme Smith, said: "CSA is doing everything in our power to ensure that our top priority, which is the health, safety and welfare of players, support staff and all involved in this series is safeguarded.
"With that in mind, we have made the joint decision to cancel today's match. We are deeply regretful of the situation we find ourselves in after the amount of time and energy that has been put in place to host a successful tour.
"We are in continuous talks with the ECB as we navigate the situation under the guidance of our combined medical teams."
Sky Sports Cricket's Michael Atherton said: "There is a suspicion the results might be false positive - whether the readings are unusual, who knows? They have sent those results to be confirmed or otherwise and that will be key.
"It is very difficult to see these games and this tour going ahead if two members of the touring party are confirmed to be positive. If they are false positive and the touring party is clear, then there may be a chance of finishing this tour.
"I think [two games] is the absolute best we can hope for - there is no way you will get three games in now, I don't think that's feasible.
"Players will want some breathing space if those results come back as false positives to be assured that everything is okay, so pushing them back two days to Tuesday, Wednesday would allow that.
"But it all depends on these two tests. If they come back as confirmed positives, then I'm afraid the tour is done for and then there are significant question marks about whether those players have to remain."
Roy Davies, general manager of the Vineyard Hotel, issued a statement revealing the members of staff had tested positive on Friday and had since been isolating.
"The Vineyard Hotel can confirm that two staff members tested positive for Covid-19 on Friday, December 4 following the positive test of a South African player on Thursday, December 3," he said.
"At this stage, it is not clear how the staff members became infected as neither have left the bio-secure area since November 16 and they do not work on the same team or in the same area. Our Covid response team is endeavouring to establish all the facts and contact tracing is underway.
"Our number one priority is the safety and wellbeing of our staff and guests and we have placed all our resources and efforts into investigating and resolving the situation.
"Both members of staff and a player who also tested positive on Friday are currently isolated in on-site apartments some distance from the hotel which have been kept sterilised and available for this purpose."