(Adds resident, UN, acting president comment)
MAIDUGURI, Nigeria, Aug 11 (Reuters) - Nigeria's military raided a United Nations compound in the northeast of the country on Friday and said it was searching for members of Islamist militant group Boko Haram.
The raid in Maiduguri, a city at the epicentre of Boko Haram's insurgency, could damage an already tense relationship between the military and the United Nations and aid groups tackling one of the world's largest humanitarian crises.
Nigeria's military said it had searched the UN compound and at least 30 other properties because a source had told the army that members of Boko Haram were hiding in the area.
Residents in the vicinity told Reuters that soldiers had arrived with more than 10 military pick-up trucks and two armoured vehicles, demanding people outside leave the area and searching properties for bombs and anyone hiding.
The military also said in its statement that "the property did not carry a UN designation," and the operation "was successfully concluded but no arrest was made because the suspects were not found."
Samantha Newport, a spokeswoman for the UN Office for the Coordination of Humanitarian Affairs, said: "Members of the Nigerian security forces entered a United Nations base for humanitarian workers in Maiduguri ... without authorisation."
The security forces, who arrived at about 5 a.m., "carried out a search of the camp and left at about 0800 hours", she said, adding that at the time the UN had no information on the reason for the unauthorised search.
"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," Newport said.
The UN's top representative in Nigeria, the humanitarian coordinator, is communicating with the government about the incident, said Newport.
She also challenged the military's assertion that the compound did not carry any UN designation, saying the property is registered and the Nigerian government and military have maps from June with all UN locations marked on them.
A Nigerian presidency spokesman declined to comment, saying the incident was a military issue. Many Nigerian politicians and aid workers say privately they are sceptical of some of the military's statements.
Last month, the army said it had rescued all members of an oil survey team kidnapped by Boko Haram and that nine soldiers and a civilian were killed.
It later emerged that at least 37 people were killed including soldiers and five members of the team from a local university, and three other members of the crew were kidnapped by the insurgents.
The eight-year insurgency has driven at least 2 million people from their homes and almost 7 million need humanitarian assistance. 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 to the response this year, though agencies say more is needed to keep the crisis from worsening.
The army has been accused of human rights violations including unlawful detention, sexual abuse and extrajudicial killings.
In February, an air force strike on a refugee camp killed up to 170 people, among them at least six Red Cross aid workers. The military said the attack was an accident.
Also on Friday, Nigeria's Acting President Yemi Osinbajo launched a panel to investigate the military's human rights compliance.
"If left unaddressed, these allegations are capable of undermining the good work of the armed forces" and "will also leave those who may have been victims of such abuses without any recourse to justice," Osinbajo said. (Reporting by Ahmed Kingimi in Maiduguri, Ardo Hazzad in Bauchi and Paul Carsten in Abuja; Additional reporting by Camillus Eboh, Alexis Akwagyiram and Felix Onuah in Abuja and Ola Lanre in Maiduguri; Editing by Andrew Bolton)