Nigerian soldiers have surrounded the Maiduguri office of Action Against Hunger, an international nongovernmental working in Borno State.
Witnesses said soldiers took over and sealed the property Wednesday night.
By Thursday morning, a PREMIUM TIMES reporter saw two military trucks packed at the entrance to the office.
Some workers told PREMIUM TIMES they were chased away by the soldiers and asked to stay off the property.
The staff members said they reported for work Thursday morning to meet armed soldiers taking over the building.
"We really don't know what is happening but no one is allowed to go near the gate and even the soldiers won't talk to any one," one staff told PREMIUM TIMES. The staff did not want to be named since he was not permitted to speak on the matter.
The spokesman of the 7 Division Nigeria Army, Ado Isa, did not respond to telephone calls and text message.
The same message was not responded to by Ayodele Famuyiwa, a group captain, who coordinates communications at the Operations Lafiya Dole Theatre Command.
The country director of ACF in Nigeria, Shashwat Saraf, confirmed the development to PREMIUM TIMES on phone.
He said they were yet to be communicated by the military on why the military sealed off the office.
"We are actually surprised that our Maiduguri office has been sealed off by soldiers, but we have no idea why and we have not been communicated," he said.
"So we have been trying to find out; I will say we hope to get more information if there is any confusion before the end of the day. As it is right now, we have no information, though it happened since last night. We will get back to you if we have more information," Mr Saraf said.
In July, the Action Against Hunger lost one of its staff while six others are still missing after Boko Haram gunmen attacked a convoy of the humanitarian workers in Borno State.
In a video clip released on Wednesday, the six humanitarian workers and staff of Action Against Hunger (ACF) who were abducted begged the Nigerian government to help get them released.