The Medical Charity – MSF – is demanding for an explanation from the authorities for the attack last week on their staff in Leer in Unity State.
It said armed men entered its compound, intimidated staff with threat of violence on Friday and Saturday.
The charity now says it needs security assurances from both parties for it to resume medical assistance.
“Our message to those responsible is that we need explanation for what happened,” said Jacob Kuehn, spokesman.
“We want to return our medical supplies and we want assurances that we can continue to operate in Leer, because we need to revive that medical assistance…”
The armed men stole medical supplies, vehicles, technical equipment, and personal belongings.
The incident happened amid renewed fighting in the area.