The club said players have returned to training on a "staggered basis".

On Monday, Premier League and English Football League clubs chose to fulfil festive fixtures despite ongoing Covid-19 disruption.

"Unfortunately, the games against Brentford and Brighton & Hove Albion were postponed as the club had no option but to request that the matches were rearranged," said a Manchester United statement.

"The Premier League board took the decision to call the fixtures off, based on guidance from medical advisors."

It added the reopening will give interim manager Ralf Rangnick and his squad time to prepare for their next fixture against Newcastle United at St James' Park on Monday, 27 December (20:00 GMT).

Manchester United recorded a number of positive Covid tests among players and staff following their 1-0 win at Norwich on 11 December, which were confirmed by PCR tests a day later.

Six Premier League games were postponed at the weekend and the league confirmed this week there had been 90 new positive cases from 12,345 tests on players and staff between 13 and 19 December.