The Cameroonian midfielder looks set to leave the Nou Camp after two disappointing seasons in just under six months’ time, with manager Tata Martino ready to cut him loose.
Song departed Arsenal in 2012 to join Barca In a £15m deal, however he has failed to hold down a first-team berth with the Catalan giants.
United chief David Moyes is said to have in excess of £100m to spend in a bid to rebuild his squad, and he is rumoured to have earmarked the versatile 26-year-old as a key target.
The Scot is desperate to add some dynamism to his central options, with the likes of Michael Carrick and Tom Cleverley having failed to convince this term.
Song is known for his physicality, but has also developed a reputation for his ability on the ball and vision.
The former Gunners hero is likely to jump at the chance tor return to England in a bid to get his career back on track, despite having suggested in the past they he is committed to Barca.
As well as United, Manchester City and Arsenal have also been linked with his signature.