Parts of Yemen are seeing their highest levels of acute malnutrition in children, heightening warnings that the country is approaching a dire food security crisis, a U.N. report said on Tuesday.

Drivers of malnutrition in Yemen worsened in 2020, as the coronavirus pandemic, economic decline, floods, escalating conflict and significant underfunding of this year's aid response have compounded an already bleak hunger situation after almost six years of war.

"We've been warning since July that Yemen is on the brink of a catastrophic food security crisis. If the war doesn't end now, we are nearing an irreversible situation and risk losing an entire generation of Yemen's young children," said Lise Grande, U.N. Humanitarian Coordinator for Yemen.

According to a U.N. Integrated Food Security Phase Classification (IPC) malnutrition analysis of south Yemen, acute malnutrition cases in children under five have increased about 10% in 2020, to more than half a million.

Cases of children with severe acute malnutrition rose 15.5%, and at least a quarter-million pregnant or breastfeeding women also need malnutrition treatment.

About 1.4 million children under 5 live in south Yemen, which is under the control of the internationally recognised government of Yemen. IPC data for north Yemen, where most Yemenis live and which is controlled by Iran-aligned Houthi authorities, is not yet available.

Famine has never been officially declared in Yemen. The U.N. says the country is the world's largest humanitarian crisis, with 80% of the population reliant on humanitarian aid.

Nutrition and other services that keep millions from starvation and disease are gradually closing across Yemen amid an acute funding shortage this year.

The U.N. says it had by mid-October received only $1.43 billion of the $3.2 billion needed for the entire 2020 Yemen humanitarian response. Programmes have started to close and scale down.

The organisation said it needs $50 million urgently to boost nutrition programmes.

A Saudi-led coalition intervened in Yemen in March 2015 to restore the Yemeni government ousted from power in the capital Sanaa by the Houthi movement in late 2014.