Persistent conflict in Congo's eastern borderlands with Uganda, Rwanda and Burundi and insurrection in the centre of the country have displaced 4.3 million people internally. Last year, it led the United Nations to declare Congo a level three humanitarian emergency - on par with Iraq, Syria and Yemen.
The campaign against the ADF is expected to displace 196,300 people in Beni territory and another 173,200 people in neighbouring Lubero territory, the U.N. Office for the Coordination of Humanitarian Affairs said in a report.
More than 532,000 people in the two territories near the Ugandan border fled their homes in 2016 and 2017, largely driven out by attacks by the ADF and other armed groups as well as military responses, the report said.
"The absence of protection measures for civilians in the most affected zones risks worsening. The risk of shells falling on civilian sites ... cannot be excluded," it said.