The striker has polarised opinion since his deadline day move to Old Trafford in 2008 for a club record £30.75m.
While he was joint top scorer in the Premier League last season, Berbatov was left out of the Champions League final squad by Sir Alex Ferguson and has been often overlooked this term as well.
Berbatov has scored 55 goals in 144 appearances for the club and, although Ferguson has signalled his intention to trigger the one-year extension to the Bulgarian's contract, many see this as a ploy to protect Berbatov's value.
He could have left for a knock-down price this month with clubs aware of his contract situation but Ferguson moved to quash any hope of a quick sale by speaking of his desire to give Berbatov an extra year.
However, it is understood that United are planning a squad overhaul in the summer and Berbatov appears to be a high-profile victim.
Bayern have reportedly approached United regarding a deal for Berbatov and while no move will happen this month, the Premier League champions are said to be open to the idea of selling Berbatov in the summer.