The England international is keen on a return to Dortmund after a difficult two years at Old Trafford.
BILD says a move to Borussia Dortmund is now being discussed.
Dortmund sporting director Kehl is in continuous contact with Sancho's management team.
However, so far there has been no contact between the clubs. A loan is the only option open to Dortmund given the fee United are likely to demand.
Sancho's contract with United runs until the summer of 2026, with an option for another year.