The number of people who have fled their homes inside the Democratic Republic of Congo could nearly double to 760,000 in the next months, the UN refugee agency warned on Tuesday in Geneva, reported dpa.
Fighting broke out in April between government forces and the M23 militia, displacing some 390,000 people so far this year.
In addition, 60,000 have fled to neighbouring Rwanda and Uganda, the office of the United Nations High Commissioner for Refugees (UNHCR) said.
The government's military engagement with the M23 has created a security vacuum, allowing other armed groups to re-emerge in the tense eastern parts of the country.
The UN High Commissioner for Human Rights, Navi Pillay, recently cited reports that groups not related to M23 have massacred hundreds of people in North Kivu province since May.
UNHCR called on the international community to donate an additional 40 million dollars to provide aid to the refugees.
Much of the violence in eastern Congo stems from the 1994 genocide in Rwanda, which spilled over the border to DR Congo.