Ighalo has been banned from the club’s training ground, over fears of a potential coronavirus risk, the UK Mirror reports.
Ighalo moved to United from Chinese club Shanghai Shenhua on a six-month loan deal.
The Nigerian striker has been working on his fitness with a personal trainer, at a separate location in Manchester.
This is because Ighalo was instructed to train away from United’s AON Training Complex for health and safety issues.
The club took the decision for him not to use the facilities, while he is still within the mandated 14-day incubation period.
The 30-year-old also did not travel with Ole Gunnar Solskjaer’s squad to Spain for a warm-weather training.
United were afraid that border restrictions, could see Ighalo denied entry back into the UK.