"Today, 1.8 million children under the age of five are facing acute
malnutrition, and 400,000 are affected by severe acute malnutrition," said Geert
Cappelaere, regional director of UNICEF.
"More than half" of the 14 million people at serious risk of famine in the impoverished country are children, Cappelaere told AFP late on Wednesday.
"Ending the war is not enough," he said.
"What we need is to stop the war and (to create) a government mechanism that puts at the centre the people and children.
"The war is exacerbating the situation that was already bad before because of years of underdevelopment" in the Arab world's poorest nation, Cappelaere said.
He welcomed a call by the UN on Wednesday to relaunch peace talks within a month.
He said efforts to come up with a solution in the next 30 days were "critical" to improving aid distribution and saving lives.
Cappelaere said that over 6,000 children have either been killed or sustained serious injuries since 2015.
"These are the numbers we have been able to verify, but we can safely assume that the number is higher, much higher," he said.
Since 2015, more than 10,000 people have been killed and some 22 million -- three quarters of the population -- are in need of food aid, according to the UN.
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.