Yemenis displaced by conflict carry humanitarian aid provided by a charitable organisation, March 19, 2024, on the outskirts of the northeastern city of Marib. (AFP)

Acute malnutrition is rapidly increasing in areas of Yemen controlled by the government, with the most critical cases along areas of the Red Sea coast, UN food security experts said in a report issued on Sunday.

The war between the Saudi-backed government and Iran-aligned Houthi militia, stalemated for years, has caused the economic collapse of the already widely-impoverished Arabian Peninsula country and one of the world's worst humanitarian crises.

In a report, the UN's Integrated Food Security Phase Classification (IPC) Technical Group in Yemen said malnutrition had worsened from the combined effect of the spread of diseases such as cholera and measles, a shortage of nutritious food, a lack of drinking water and broader economic decline.

The number of children in Yemen under the age of five suffering acute malnutrition, or wasting, has risen by 34 percent compared with the previous year across government-controlled areas, the report said. This equated to some 600,000 children, including 120,000 who were severely malnourished.

For the first time, it said, "extremely critical" acute malnutrition level was reported in the southern Hodeidah lowlands, including the Al Khawkhah and Hays districts, fringing Yemen's Red Sea coast, as well as the Al Makha district of the Taiz lowlands between November 2023 and June 2024.

The report did not say whether there had been any recent deaths from severe hunger or what conditions were like in Houthi-held areas of the country.

Houthi forces hold most large urban centres of Yemen including the capital Sana'a while the Saudi-backed government is based in Aden in the south.

The Riyadh-led coalition intervened in Yemen in March 2015 after the Houthis ousted the government from Sana'a.

The multi-faceted conflict, in which several factions are vying for power, has killed tens of thousands of people.