Saracens have forfeited their European Challenge Cup game against Pau following a Covid-19 outbreak at the Gallagher Premiership club.
Tournament organisers European Professional Club Rugby said a 28-0 scoreline and five match points had been awarded to the French club, who were due to host Saracens on Saturday.
EPCR added that Saracens had informed them of a "significant number" of positive Covid-19 tests among their playing squad, meaning they could not safely fulfil the Pau fixture.
Saracens said that the outbreak had occurred within their training ground environment, reporting "several positive Covid cases" from a latest round of PCR testing on Monday.
In a statement, Saracens said: "The club has taken the immediate action of closing the training ground and isolating all players, coaches and support staff.
"We have been working closely with EPCR and PRL (Premiership Rugby) and it is with regret that our game versus Section Paloise (Pau) in the EPCR Challenge Cup on Saturday 18th December has had to be forfeited by Saracens due to our inability to field a 23-man squad for this fixture.
"In addition to positive Covid-19 cases, we have players self-isolating due to being close contacts, and a number of players who are currently injured.
"This is extremely disappointing for everyone at the club, but as always the health and well-being of our people is our priority at this time."
Yesterday, Leinster head coach Leo Cullen said they were "fully intent" on fulfilling their Heineken Champions Cup round two meeting with Montpellier in France, despite both camps reporting multiple positive Covid-19 cases.