Yemeni President Abdu Rabbo Mansour Hadi in March opened a national dialogue with the aim of drafting a new constitution and paving the way toward general elections in 2014.
Hadi took power after a political deal brought an end to the tenure of longtime President Ali Abdullah Saleh, who survived an assassination attempt at the height of the so-called Arab Spring.
U.N. Humanitarian Coordinator for Yemen Ismail Ould Cheikh Ahmed said the country's political transformation was under threat.
"There will be no political transition if we don't deal with the humanitarian situation," he said from Geneva.
Ahmed said Yemen needs about $716 million in assistance to provide relief for the estimated 7.7 million vulnerable Yemenis, though it's secured less than 30 percent of the money it needs.
National security has marred many of Yemen's political ambitions. Three aid workers with the International Committee of the Red Cross were seized at gunpoint but later released this week.