The Rugby Football Union (RFU) is reviewing if the Quilter Cup England v Barbarians fixture scheduled for Sunday 25 October can still go ahead.
In a statement, the RFU confirmed that a number of Barbarians players breached the agreed Covid code of conduct protocol by leaving their hotel bubble without permission and without informing organizers about their whereabouts.
"On their return, the players were immediately separated from the rest of the group in the bubble in order to protect its integrity," continued RFU.
"The players leaving their Covid-secure environment has resulted in a potential risk of Covid transmission from individuals outside the bubble, and even with a further round of PCR testing for this group, it will not be possible to guarantee these players are not infectious in the period up to and including the match.
"Therefore to protect the safety of other participants, these players cannot be permitted to remain with the Barbarians squad and play in Sunday’s fixture.
"If sufficient new players with an appropriate testing history and who have been meeting the code of conduct standards can be brought into the Barbarians camp then the game will go ahead.
"The RFU scheduled the Quilter Cup Barbarians fixture for performance purposes in order to provide a warmup game ahead of the postponed Italy v England Guinness Six Nations decider, however it will not compromise the safety of players to do so.
"The RFU will provide an update on the match status by 3pm on Friday 23 October. No details on the individuals who will be in or out of the revised Barbarians squad will be announced until the fixture is re-confirmed."