A message on the club's site outlines the Premier League team's new rules to the networking sites: "The club wishes to make it clear that no Manchester United players maintain personal profiles on social networking websites.
'Fans encountering any web pages purporting to be written by United players should treat them with extreme scepticism."
The bookmakers Paddy Power have been betting on which club would be the first to ban Twitter since Sunderland striker Darren Bent's summer outburst towards Tottenham Hotspur Chairman Daniel Levy over his protracted transfer to Sunderland.
Bent has built up big following on the microblogging site, with around 30,000 followers. Recently, he said he was "150% committed to the cause" after being beaten 7-2 by Chelsea.
The bookies are now taking bets on the next Premier League team to ban players from using Twitter. The favourites are Tottenham Hotspur (4/1), Liverpool (6/1), Hull (8/1).