The UN has condemned intimidation of staff and patients by armed groups in the Central African Republic (CAR).
Men armed with machetes, knives and other crude weapons entered hospitals in the past few months, the UN said, most recently in the town of Bambari.
Terrified relatives had moved patients from Bambari hospital even though they still needed treatment.
The UN said it was unclear who was carrying out the attacks, suspected of being ethnically motivated.
The conflict has led to a 70% increase in the number of internally displaced people since January 2017, the UN says.
The UN's humanitarian co-ordinator in the CAR, Najat Rochdi, said in a statement he would "hold these armed groups directly responsible for any medical complications and life-threatening conditions of patients."
Humanitarian workers have also been targeted in Bambari, with nine of their compounds attacked and looted last month alone.
The country has been in a state of chaos since mainly Muslim rebels drove President Francois Bozize from power more than five years ago.
The UN was criticised after 28 people died in April when UN peacekeepers and local security forces attempted to clear a predominantly Muslim neighbourhood of armed groups, leading to deadly clashes in the capital Bangui.