Twenty million people are at risk of starvation this year as delayed rains worsen an already brutal drought in Kenya, Somalia and Ethiopia, the United Nations warned Tuesday.

A monthslong drought has left the Horn of Africa on the verge of a humanitarian catastrophe, destroying crops and livestock and forcing huge numbers of people to leave their homes in search of food and water.

As long-awaited rains fail to materialize nearly a month into the current rainy season, "the number of hungry people due to drought could spiral from the currently estimated 14 million to 20 million through 2022," the U.N.'s World Food Programme (WFP) said.

Six million Somalis, or 40% of the population, were facing extreme levels of food insecurity and there was "a very real risk of famine in the coming months" if current conditions prevailed, the WFP said.

In Kenya, half a million people were on the brink of a hunger crisis, with communities in the north of the country especially at risk due to their reliance on livestock.

The number of Kenyans in need of assistance has risen more than fourfold in less than two years, the agency said.

Malnutrition rates in drought-hit southern and southeastern Ethiopia have surged above emergency thresholds, while the north of the country has been in the grip of a 17-month war between government forces and Tigrayan rebels.

Parts of the drought-hit Horn of Africa region are already reeling from the effects of ongoing conflict, poverty and a locust invasion, the U.N.'s Food and Agriculture Organization (FAO) said Tuesday.

"We must act now ... if we want to prevent a humanitarian catastrophe," FAO's representative to the African Union, Chimimba David Phiri, told a U.N. briefing in Geneva.

Lack of funding

The dire conditions have been exacerbated by the conflict in Ukraine, which has contributed to soaring food and fuel costs and disrupted global supply chains, WFP said.

The agency warned that a lack of funding could spell disaster, calling for $473 million (438 million euros) over the next six months.

A previous appeal in February raised less than 4% of the cash needed, it said.

Meanwhile, the FAO was short of more than 60% of the funds it required to meet the needs of 1.5 million people in the three countries.

"We know from past experience that acting early to avert a humanitarian catastrophe is vital, yet our ability to launch the response has been limited due to a lack of funding to date," said Michael Dunford, the WFP's regional director for East Africa.

East Africa endured a harrowing drought in 2017 but early humanitarian action averted a famine in Somalia.

In contrast, 260,000 people – half of them children under the age of 6 – died of hunger or hunger-related disorders when a famine struck the country in 2011.

Experts say extreme weather events are happening with increased frequency and intensity due to climate change.