The increasing vulnerability of civilians to armed violence in the Democratic Republic of Congo (DRC) has brought new calls for urgent regional efforts to stop the conflict.
More than 17,000 United Nations peacekeepers have proved ineffective as rebels advance.
In the past four months, more than 450,000 people in ethnically-mixed eastern Congo have fled their homes.
The UN Humanitarian Affairs chief Valerie Amos, on a visit to the Kigeme refugee camp in neighbouring southern Rwanda, said all partners in the region had to help solve the crisis.
Amos said: “The situation here is [so] terrible, people have come here spontaneously. We are doing our best to respond, but thousands of people [have been] displaced in a very short period of time. Everything has to be done, politically, for fighting to stop.”
The North and South Kivu provinces have seen hundreds of thousands uprooted, some fleeing to Uganda and Rwanda.
A recent surge in fighting drew government troops to reinforce the provincial capital Goma, exposing other areas.
Renegade soldiers known as the 23 March Movement (M23) have clashed with national army troops.
They launched their rebellion earlier this year after accusing the government of failing to uphold its end of a March 2009 peace deal to reintegrate them.
African leaders of the Great Lakes region, after a two-day summit in Uganda last week, said they would impose sanctions on any party obstructing peace in the DRC.
Rwanda denied allegations by UN experts that Rwandan military officials have supplied M23 with equipment and recruits.
Uganda rejected similar allegations.
The leaders meeting in Kampala called for a “complete halt” to the fighting.