Host UN Secretary-General Antonio Guterres lamented "an overwhelming humanitarian catastrophe" where some 24 million people, or four-fifths of Yemen's total population, require aid and protection, AP reported.
"Twenty million people cannot reliably feed themselves or their families," he said in Geneva, where the meeting is taking place. "Almost 10 million are just one step away from famine."
UN officials say they are running out of money in a country also facing a devastated health care system, a lack of jobs, continued fighting and fallout from the world's worst cholera epidemic in 2017.
The world body's "Humanitarian Response Plan for Yemen" in 2019 seeks $4 billion to reach 15 million people across the country, after raising nearly $2.6 billion last year.
Yemen’s defenseless people have been under massive attacks by Saudi Arabia and its allies for more than three years but Riyadh has reached none of its objectives in Yemen so far.
Since March 2015, Saudi Arabia and some of its Arab allies have been carrying out deadly airstrikes against the Houthi Ansarullah movement in an attempt to restore power to fugitive former president Abd Rabbuh Mansour Hadi, a close ally of Riyadh.
The Yemeni Ministry of Human Rights announced in a statement on March 25 that the war had left 600,000 civilians dead and injured until then. The war and the accompanying blockade have also caused famine across Yemen.