“An employee in the consular section of the Nigerian embassy was found dead at his home in Khartoum,” Sudanese police said in a statement.
“Preliminary investigation shows that the death was due to a criminal act and not politically motivated,” the statement added.
The Nigerian foreign ministry confirmed the death of the diplomat and described him as an “immigration attaché”.
“We have to wait for a formal report from our mission detailing how it happened,” Nigerian foreign ministry spokesman Tiwatope Elias-Fatile told AFP.
“It is so sad and we are so worried about the incident. We are not happy about it.”
Reports on social media said the diplomat had been attacked with a knife, but details have not been confirmed by Sudan’s police or Nigeria’s government.
The Nigerian is the second diplomat to have died in Khartoum in less than a year.
In August, the then Russian ambassador to Sudan, Mirgayas Shirinsky, was found dead in the swimming pool of his residence. Moscow later said he had died of a heart attack.