Martial's contract at United expires in 2019, though United have an option for a further year, but his representative has made it clear he will not stay put.
“After reflecting carefully on all the possibilities and all the parameters, Anthony has decided he wants to leave Manchester United," Philippe Lamboley told RMC Sport.
“Manchester United wanted to offer Anthony a contract extension and don't want him to leave, but we haven't been able to reach an agreement after several months of talks.
“If Manchester United, the most powerful club in the world, can't reach an agreement after eight months of negotiations, it means they don't really consider him to be an important player.
“We simply don't share their view of Anthony's future. He is disappointed, because he has shown love for the club and supporters over the last three years. I can tell you that without the unconditional love of the supporters, Anthony would've asked to leave Manchester United sooner."