Some 400,000 children are at risk of starving to death in the Democratic Republic of Congo, the United Nations says.
Thousands of families in the Kasai region fled to the bush, where they stayed for months, short of food and water, many have already died.
The Kasai region, once one of the most prosperous and peaceful in DR Congo, descended into violence in 2016.
Long-simmering resentment exploded into rebellion against the government.
In December 2017, the UN declared the crisis in DR Congo as the highest level of emergency - the same as Yemen, Syria and Iraq.
The UN children's agency Unicef has appealed for $88m (£65m) in aid for Kasai.
Unicef spokesperson Christophe Boulierac has just returned from a trip to Kasai.
"I was really shocked by what I saw there," he told the BBC.
Mr Boulierac said he had visited three hospitals and seen children suffering from severe acute malnutrition. When he returned a few days later, several of the children had died.
"We are not saying that children are at risk of dying of malnutrition in Kasai, we are saying that children are already dying, they are dying, they have died, in silence, in the bush".
What is the fighting about?
Some of those who fled the fighting are now returning to their destroyed villages, where no crops have been planted.
Unicef estimates that almost four million people in Kasai need aid. Malnourished children are the most vulnerable.
The organisation says it wants to scale up feeding centres, train medical staff, and support children who were forcibly recruited by armed groups.
The rebellion broke out in 2016 after the government refused to recognise a traditional chief, Kamina Nsapu, and imposed its own man instead.
Both his supporters and the army have been accused of widespread atrocities.
Reproduced under licence from BBC News © 2018 BBC