The UN head was "shocked and saddened" by the loss of life and offered his condolences to the grieving families and the injured.
"The perpetrators of this attack and those responsible for the continuing brutal attacks in the northeast of the country," the secretary-general's office said, "must be brought to justice."
The explosion took place during the morning rush hour at the Nyanya bus terminal. According to initial reports 16 luxury buses and 24 other vehicles were burned as the bomb exploded Monday morning, injuring some 124 people. Nine ambulances were seen taking the deceased and inured to local hospitals.
No one has yet claimed responsibility for the attack although there is suspicion that Islamist militant group Boko Haram was responsible.