Nigerian forces conducted an unauthorized search of the main U.N. humanitarian base in the country's volatile northeast, the United Nations said Friday.
U.N. officials said the Nigerian troops, in a pre-dawn raid, forced their way into the base in Maiduguri, the city where the Boko Haram Islamist insurgency began. The search lasted about three hours, one official said.
The military confirmed the incident in a statement Friday, saying the action was part of its efforts to search for Boko Haram members. It said no suspects were found.
Rumors were circulating in Nigeria that Boko Haram leader Abubakar Shekau had taken refuge in one of the U.N. camps in Nigeria.
The action was likely to further strain an already tense relationship between Nigeria's government and aid groups.
"The United Nations is extremely concerned that these actions could be detrimental to the delivery of lifesaving aid to the millions of vulnerable people in the northeast of Nigeria," said Samantha Newport, a spokeswoman for the U.N. Office for the Coordination of Humanitarian Affairs.
The military plays a key role in the northeast, particularly outside Maiduguri in the state of Borno which has been the worst hit by Boko Haram.
Aid agencies mostly rely on the army and its convoys for access to other parts of the state, and in many camps for displaced people it is the military distributing food and medical supplies.
A spokesman for U.N. Secretary-General Antonio Guterres said the United Nations had formally complained to the Nigerian government.
"There have been contacts — we understand from the government that this was a mistake. The raid should not have happened," Stephane Dujarric said Friday at a daily briefing in New York.
News of the raid came as Nigeria's Vice President Yemi Osinbajo launched a long-planned presidential panel to investigate allegations of human rights abuses by the military. The army has been accused of unlawful detention, sexual abuse and extrajudicial killings.
Since 2009, Nigeria has struggled to stop deadly raids and suicide attacks by the Boko Haram extremist group, which says it wants to create a strict Islamic state in Muslim-majority northern Nigeria.
Most land retaken
Last year, the Nigerian army was able to retake most of the territory captured by Boko Haram,,with the help of neighboring countries. However, Boko Haram has continued to attack markets and public places.
The militant group has killed an estimated 20,000 people overall, and the violence has forced more than 2 million Nigerians from their homes. Tens of thousands live on the brink of famine, and millions more lack secure access to food.
More than $650 million has been given by the international community in response this year, though agencies say more is needed to keep the crisis from worsening.
Some information for this report came from Reuters.