The 31-year-old defensive midfielder still has three years remaining on his contract with the French club, but he was believed to have had an agreement with his employers that he would be allowed to leave for free this summer.
However, it now appears that Marseille are not willing to allow the former Real Madrid and Portsmouth man to walk away, and will demand a fee for his sale.
Diarra was due to occupy the defensive-midfield berth in France’s line-up at the ongoing UEFA European Championship on home soil, only to suffer an injury before the tournament began, ruling him out and presenting an opportunity for Leicester City’s N’Golo Kanté to take his spot in the side.
Diarra previously worked under new United boss José Mourinho at Real Madrid, where it was reported that the player was not a great fan of Mourinho’s methods. But the Portuguese coach valued Diarra’s athleticism and tactical discipline, and it appears he is now poised to make the Frenchman an offer to join his new-look United side.