Martial, 22, joined United from Monaco in the summer of 2015, and has scored 36 times in 137 appearances for the club in all competitions.
He scored nine Premier League goals for the Red Devils last season, but his future has been the subject of much speculation over the last 12 months, and it has been reported that United have ‘lost faith’ in him.
Martial has only played 60 minutes of Premier League football for the 20-time English champions this term, and Chelsea, Tottenham Hotspur and Inter Milan are all believed to be monitoring developments.
However, according to The Sun, United’s board are refusing to sell Martial due to the fact that the English club would have to pay Monaco half of any profit they make on the attacker.
The same report also claims that United are still confident that Martial could become a ‘world-class player’ during his time at Old Trafford, despite falling out of favour under Jose Mourinho.
Martial has thus far cost United in the region of £44.5m, but the deal could eventually reach £60m.