Ex-Celtic and Leicester winger Steve Guppy, former Whites striker Brian Deane and midfielder Craig Hignett have all been added to the squad for the trip to Sweden to play against local opposition, first against FC Bodens (14th) and then FK Pitea (17th).
Guppy is available on a Bosman free transfer and Deane, who was at Elland Road between 1993 and 1997, was at West Ham before being released last season.
And former Middlesbrough, Barnsley and Leicester midfielder Craig Hignett has been training with United this week.
Full squad for Sweden:
Paul Butler (c)
Gary Kelly
Michael Duberry
Frazer Richardson
Matthew Kilgallon
Clarke Carlisle
Eirik Bakke
Matthew Spring
Steve Guppy
Craig Hignett
Julian Joachim
Michael Ricketts
Danny Pugh
Danny Cadamarteri
Aaron Lennon
Scott Carson
Brian Deane
Jermaine Wright
Gary Kelly
Michael Duberry
Frazer Richardson
Matthew Kilgallon
Clarke Carlisle
Eirik Bakke
Matthew Spring
Steve Guppy
Craig Hignett
Julian Joachim
Michael Ricketts
Danny Pugh
Danny Cadamarteri
Aaron Lennon
Scott Carson
Brian Deane
Jermaine Wright
Lucas Radebe is still a part of Kevin Blackwell's plans for next season, but he was not expected to go on tour and be part of a full pre-season training schedule anyway due to the condition of his knees.