Manchester United's players and staff 'were hit by a bout of suspected food poisoning' following their UEFA Europa League trip to Moldova last week.
Erik ten Hag's team played Sheriff Tiraspol in the Moldovan capital Chisinau on Thursday night, winning 2-0 thanks to goals by Jadon Sancho and Cristiano Ronaldo.
They then returned to Manchester by private plane but members of the party began to feel unwell on Friday.
According to The Sun, up to 12 in the United camp were affected with a handful of players missing training on Friday and others on Saturday.