United have now confirmed neither Sesko nor Mbeumo will take part in international fixtures at the end of March, but full-back Noussair Mazraoui will join Morocco's camp after fighting off a bout of illness.
A statement from United reads: "Manchester United defender Noussair Mazraoui has recovered from an illness and will link up with Morocco, ahead of their friendlies against Ecuador and Paraguay. Bryan Mbeumo has had to withdraw from Cameroon’s squad for friendlies against Australia and China, as a precaution, after being substituted in the 71st minute of Friday night's 2-2 draw with Bournemouth.
"Benjamin Sesko has also had to withdraw from international duty. The centre-forward will miss Slovenia’s friendlies against Hungary and Montenegro, in order to ensure that he fully recovers from an issue that United have been carefully managing throughout recent weeks."