Aid agencies have warned that years of drought and conflict have left eastern Africa on the brink of famine, with 16 million people facing the threat of starvation.
World leaders gathering at a special conference in London today will hear that Somalia, Ethiopia and Kenya are on the brink of a humanitarian disaster.
Aid experts are warning an entire generation could be lost.
Famine has already been declared in South Sudan, where a million people are facing starvation.
UN Secretary General Antonio Guterres will appeal for governments to boost funding to avert a famine taking hold across the region.
British Prime Minister Theresa May is hosting the high-level conference to consider the humanitarian crisis and security situation in Somalia.
Somali President Mohamed Abdullahi Mohamed Farmajo will also speak at the conference.
The meeting will focus on the agreement of a security pact and the adoption of a "new partnership for Somalia" to deliver the support and reforms the country needs over the next four years.
Across east Africa, 19.5 million people do not have a regular supply of safe drinking water.
In South Sudan 100,000 people are suffering from famine, with nearly a million on the brink of starvation. An estimated 4.9 million - half the population - do not have enough food to eat.
Three years of drought in Somalia has left 363,000 children facing severe malnutrition, and 6.2 million people, half the population, are in urgent need of humanitarian assistance.
The UN has warned the situation is worse than in 2011 before the declaration of famine that claimed 260,000 lives.
In Kenya 2.7 million people have inadequate food supplies, while in Ethiopia the worst drought in decades has left 5.6 million people severely food insecure and 300,000 children malnourished and at risk of dying.