UN spokesman Stephane Dujarric told reporters today that an unidentified group was involved in Wednesday's incident in Nyala in South Darfur.
He said "the mission strongly condemns this attack which constitutes a violation of international law" and calls on Sudan's government "to swiftly apprehend the perpetrators and bring them to justice."
Dujarric said the United Nations joins the mission in extending "deepest condolences" to the family of the peacekeeper, who was not identified, and to the Nigerian government.