The defender was on Tyneside last week for a medical ahead of a £7million move from Anderlecht.
However, the deal can’t be finalised until the FA meets to consider an application from the club for a Governing Body Endorsement, which is needed for the 20-year-old to get a visa.
A panel won’t meet until Thursday, meaning Mbemba is in limbo this week.
Thanks to Mbemba’s experience with DR Congo, he will fulfill the criteria needed for a work permit.
Mbemba will become the club’s third summer signing after midfielder Georginio Wijnaldum and striker Alexsandar Mitrovic once the paperwork is completed.