It's estimated more than two million children in the Democratic Republic of Congo are at risk of dying from severe acute malnutrition if they do not get aid, the United Nations warns.

UN humanitarian chief Mark Lowcock will meet donors next week in the country where conditions in many areas are worsening, UN spokesperson Jens Laerke told a Geneva briefing.

"We have a great responsibility in the DRC ... now is the time to stay the course," Laerke said.

The two million children at risk of starvation include some 300,000 in the Kasai region, Bettina Luescher of the UN's World Food Programme said.