The Premier League say Manchester United's match at Brentford was postponed following 'guidance from medical advisers due to the exceptional circumstances of an ongoing Covid-19 outbreak' at the club.
United closed first-team operations at their Carrington training complex for 24 hours on Monday after a number of players and staff returned positive lateral flow tests.
The Manchester Evening News is aware of at least four positive cases but the club has declined to specify how many players and members of staff have tested positive.
United had been in discussion with the Premier League about whether the Brentford match should go ahead and the postponement of the scheduled 7.30pm Tuesday night kick-off was confirmed just before midnight.
The Premier League said in a statement: "The Premier League Board has decided to postpone Brentford’s home fixture against Manchester United, due to be played on Tuesday, 14 December at 19.30 GMT.
"The decision was taken following guidance from medical advisers due to the exceptional circumstances of an ongoing COVID-19 outbreak within Manchester United’s squad.
"First-team operations at the club’s Carrington Training Complex were closed down today to help control the outbreak and minimise risk of further infection among players and staff.
"The League wishes a quick recovery to those players and staff with COVID-19. The postponed fixture will be rearranged in due course.
"With the health of players and staff the priority, and in light of the recent rise in COVID-19 cases across the country, the Premier League has reintroduced Emergency Measures.
"These include protocols such as more frequent testing, wearing face coverings while indoors, observing social distancing and limiting treatment time."
It is understood some of United's Under-23 players have also tested positive. The academy and women's teams are able to continue training at Carrington because of the segregation of bubbles.
No new date for the fixture has been announced.
