Aid workers in Ituri province in the east of the Democratic Republic of Congo say thousands of displaced people have been arriving in the town of Beni.
They are fleeing a series of attacks by Allied Democratic Forces (ADF) Islamist rebels in the province.
More than 90 people have been killed over the past week in attacks on at least 18 villages.
Attempts by the armies of DR Congo and Uganda to crush the rebels have made little progress.