Ulster Rugby have confirmed that four of their players have tested positive for Covid-19, and as a result, their Guinness Pro14 Rainbow Cup game against Scarlets has been cancelled.
The match was due to take place at Kingspan Stadium on Saturday evening.
The province say the players are asymptomatic but that PCR tests carried out on Wednesday led to the positive cases being detected and the quartet are now self-isolating.
Ulster have also suspended all senior and academy training sessions, with further PCR testing of all players and staff due to take place on Friday.
Scarlets have been awarded four points for the game as there is no available window for it to be re-fixed.
A statement from the province confirmed that the decision to cancel the fixture was reached with "both the league and Ulster Rugby [having] followed the guidance established by the Pro14 Rugby Medical Advisory Group, and had the full support of the Public Health Agency."
Ulster Rugby CEO, Jonny Petrie, added: "We appreciate the news that our upcoming fixture is cancelled will be deeply disappointing for our supporters, particularly those who were due to join us at Kingspan Stadium on Saturday, but we are in complete agreement that the collective decision to cancel the match is the correct one.
"Our priority continues to be the health and safety of our players and staff, as well as the wider community, so we will continue to work closely, together with the IRFU, with the Public Health Agency to ensure that we follow the necessary public health advice, as we provide support to the individuals involved."
500 tickets had been sold for the fixture, as restrictions related to the pandemic continue to be reduced in the north, but refunds will now be issued.