More than 100,000 people have been displaced by factional fighting and lawlessness in Burkina Faso, most within the past two months, according to a U.N. report published on Tuesday.
"Burkina Faso is, for the first time in its history, facing massive internal displacement," the report said.
"Repeated raids by armed groups and insecurity in the regions of Centre-Nord, Nord and Sahel have also triggered an unprecedented humanitarian emergency."
The government and humanitarian groups had begun a $100 million aid plan to help 900,000 people, it said.
Burkina Faso is a landlocked country in West Africa that borders the Sahel region countries of Niger and Mali to the north where militant groups, some linked to al Qaeda and Islamic State, have carried out attacks for years.
As well as an Islamic insurrection in the north, in 2018 Burkina Faso began suffering attacks by unknown militants in the east and attacks in the capital and elsewhere perpetrated by the Group for the Support of Islam and Muslims (JNIM).
That militant group is active across the Sahel, according to a report by the International Crisis Group (ICG) think tank.
"For the first time since independence, Burkinabé state authorities have lost control of parts of the country," said the ICG report, published last month.
The army has stepped up operations in response to worsening security across northern Burkina since last year. But rights activists have accused it of carrying out extrajudicial killings and arbitrary arrests that could worsen instability.
On Saturday, Foreign Minister Alpha Barry said incidents of violence had now spread to the country's southern border with the coastal West African countries of Togo, Benin, Ivory Coast and Ghana.
"This threat is gaining ground," Barry told the annual Munich Security Conference. "It's no longer just the Sahel, it's coastal West Africa and the risk of spreading regionally."