DR Congo's army has resumed hostilities with rebel forces again
The UN says about 200,000 people have been displaced by renewed fighting in the eastern Democratic Republic of Congo in the past two months.
Previously the United Nations had reported half that number.
Concern has been rising in the east of DR Congo, where the army has been battling fighters loyal to renegade General Laurent Nkunda.
Up to two million people are thought to have been displaced in the Kivu area since 2007, the UN says.
The UN says this vast displacement means many people are malnourished and some were dying of hunger.
Charles Vincent from the UN World Food Programme said: "The capacity of the World Food Programme and other humanitarian organisations is stretched to the limit [and] the situation has begun to deteriorate in the last [few] weeks."
"There is an enormous need for the women who have been abused," he added, saying that half the number of rapes in DR Congo are committed in Kivu.
EAST DR CONGO ARMED GROUPS
FDLR- Rwandan Hutus, accused of 1994 genocide
CNDP - Gen Nkunda's Tutsi forces
The UN says that the population needs 33,000 tonnes of food or $46m (£29m) worth of supplies by March 2009.
A UN force has failed to halt fighting in the east, where violence has intensified since August between government troops and Gen Nkunda's forces.
A peace deal was signed in Goma at the end of January between the government and the groups that have fought for control of eastern DR Congo.
But rebel forces have rearmed and renewed violence broke out in August.
The UN has some 17,000 peacekeepers in DR Congo and they have intervened in the recent fighting to try to keep the two sides apart.
But it is understood President Joseph Kabila refuses to talk to Gen Nkunda, calling him a terrorist.
Gen Nkunda signed a peace deal in January following fierce fighting in 2007.
But he has always refused to disarm while Rwandan Hutu rebels still operate in the area, as he accuses them of attacking his Tutsi community.