Mr Lundberg, however, noted that in spite of the incident, UN's relationship of trust and collaboration with the government of Nigeria remained intact.
"One of such included a property, which was said to be occupied by the United Nations staff members, although the property did not carry a UN designation".
"The humanitarian crisis in Nigeria's north-east is one of the most severe in the world today", said Kallon.
But confirming the raid in a press statement, Head, Communications UN Office for the Coordination of Humanitarian Affairs (OCHA), Miss Samantha Newport said, "On 11 August 2017, at circa 0500 hours, members of the Nigerian security forces entered a United Nations base for humanitarian workers in Maiduguri, northeast Nigeria, without authorization".
The incident, which took place on Friday, had raised concerns among members of the worldwide community with the United Nations directing its humanitarian workers operating in the state to remain indoors. It has forced the Boko Haram Terrorists (BHTs) to change tactics and resort to employment of suicide bombers to target military locations and the populace. The operation was successfully conducted as over 30 houses were searched.
He said the United Nations humanitarian office in Maiduguri had on Thursday announced the suspension of its humanitarian operations after a misunderstanding with the military. The clearance operations effort has been yielding several successes.
"It therefore became expedient to take preemptive action by combing the general area through a cordon and search operations".
In a separate statement, Ibrahim Attahiru, a commander of Nigeria's operations against Boko Haram, said the army was not trying to block the United Nations' activities.
In a statement emailed to journalists on Saturday morning, Shettima's spokesman, Isa Gusau, said given the critical intervention humanitarian workers have making in the affairs of internally displaced persons, Governor Kashim Shettima was anxious and had to place a phone call with the Deputy Secretary-General of the United Nations, Amina Mohammed.