The 21-year-old made six appearances during a loan spell with the Blades last season and has featured for the Red Devils during their pre-season tour of South Africa this summer.

Having signed right winger David Cotterill from Wigan already this summer, Blackwell is keen to give himself a similar option down the opposite flank.

"We already have the likes of Stephen Quinn and Chris Armstrong who can play wide and lock things up to balance things out in that way but we might need someone who can provide something different," Blackwell told the club's official website.

"There is a possibility that we might still be able to do something with Lee and have asked Sir Alex to keep us informed.

"Lee has said he would like to come back because he enjoyed his time here - as did the other lads who came on loan last season - which is a good mark for this club."