The Daily Mail claim the new structure of the Football League will mean many Red Devils youth stars will make a switch.
The emergency window - which allowed clubs to loan players for three months - has been abolished for the upcoming season.
It means those United players who need the experience of first-team football must secure a move before the beginning of September or face a wait until January.
And it makes things more complicated for Jose Mourinho as Premier League clubs will no longer be able to recall players at short notice.
Under-21 boss Warren Joyce said after their 5-1 win at the Class of 92’s Salford City that some players needed to play with older professionals to develop.
“We've had two games against two non-League sides (the other against Altrincham) so playing against men is what we're looking for to develop the players,” he said.
“I thought we acquitted ourselves very well. There were a lot of positives and we've no injuries.
“I’m pleased to get through it. Fitness is a major part this side of the season but it was a proper test.
“It's funny at this stage of the season because there's a lot of lads who you don't know what's going to happen to them. You're just trying to get them fit and playing a certain way.”
United youngsters James Wilson, Tyler Blackett, Sean Goss, Kieran O’Hara and Josh Harrop could be on the move, according to the reports.
