If an offer comes in the January transfer window he will be allowed to leave on a free transfer and United could offload his £14k-a-week wages into the bargain.
Wilcox joined Leeds United in a shock £3m switch from Blackburn Rovers in December 1999, yet another example of Leeds' transfer extravagances under Peter Ridsdale.
"Jason is not in the manager's plans," said a club spokesman. "He will have to look elsewhere for regular football."