Nigerias military on Friday suspended UNICEF from operating in the countrys ravaged northeast over claims it was training "spies" who are supporting Boko Haram jihadists.
The military said that the United Nations children's agency had on December 12 and 13 held workshops in the northeast city of Maiduguri training people for "clandestine" activities that are "sabotaging" counterterrorism efforts.
Boko Haram's Islamist insurgency has killed more than 27,000 people since it began in 2009 and triggered a humanitarian crisis in the wider Lake Chad region, where the jihadists have stepped up attacks in recent months.
"There is credible information that some of them are indulging in unwholesome practices that could further jeopardise the fight against terrorism and insurgency, as they train and deploy spies who support the insurgents and their sympathisers," said the press release signed by Colonel Onyema Nwachukwu.
"Consequently, the Theatre Command Operation LAFIYA DOLE is suspending the operations of UNICEF in the North East theatre until further notice."
A UNICEF spokesman said the organisation was working to verify the information.
"It's self explanatory, when you read it you will understand everything," army public relations director Brigadier General Sani Usman said about the suspension statement.
Boko Haram's bloody uprising in northeastern Nigeria has spread to neighbouring Cameroon, Chad and Niger, leaving 1.8 million people homeless and millions dependent on aid for survival.
Nigeria's President Muhammadu Buhari, who came to power in 2015 pledging to end the violence, is under increasing pressure to act as he gears up to seek re-election in a February ballot.
He has come under attack for previously claiming the Islamists were "technically defeated".
The Nigerian military has hit out at media reporting casualty figures of the attacks and even threatened legal action against organisations for publishing unofficial death tolls.
It has also dismissed reports from international human rights organisations that it has committed human rights violations and war crimes during its fight against Boko Haram.
Amnesty International on Friday condemned the suspension and called on Nigeria to reverse the decision.
"We see the suspension of UNICEF as part of a wider drive to intimidate international humanitarian and human rights organisations who are working to save lives in this devastating conflict," said Amnesty's Nigeria director Osai Ojigho.
"The Nigerian army has accused UNICEF of 'aiding Boko Haram' -– an absurd charge. The suspension of UNICEF will in fact deprive those whose lives have been devastated by the Boko Haram conflict from receiving much-needed humanitarian assistance," Ojigho said.