Munster have had to to remain in Cape Town after a member of their travelling party tested positive for Covid-19.
The Irish province were due to fly home on Sunday after their URC match away to the Bulls on Saturday was postponed following the detection of a new Covid-19 variant in South Africa.
"In taking all precautions and prioritising the health and wellbeing of everyone, Munster will not travel today and will return to their hotel for an isolation period as a matter of priority," a club statement said.
"The province will await further guidance from the health authorities."
The statement did not say whether the positive test was the Omicron variant.
Munster are one of several European rugby union teams that were in South Africa when authorities raised the alarm about the new Omicron coronavirus variant.
After arriving at their hotel in Cape Town late on Saturday night, the squad underwent a round of PCR testing ahead of Sunday's possible departure, and it was that round of testing that returned a positive case.
Travel restrictions from six southern African countries took effect in the UK from 12:00 GMT on Friday.
Fixtures to be held this and next weekend in South Africa will be rescheduled.