United agreed a last-minute extension of Ighalo's loan with parent club Shanghai Shenhua.
The first loan deal, which commenced in January, expired on Sunday.
The Daily Mailsays United have agreed to pay £130,000 of his £300,000-a-week contract.
They will also fork out another £6m in loan fees to Shenhua.
There is also no obligation or option to make Ighalo's transfer permanent in the new loan deal.
30-year-old Ighalo scored four goals in eight appearances for United before games were suspended.