More than 10,000 children have died amid the violence and suffering of Yemen's ongoing conflict, United Nations Secretary-General Antonio Guterres said Wednesday as international aid pledges once again fell billions short.

"Yemen may have receded from the headlines, but the human suffering has not relented. For seven years and counting the Yemeni people have been confronting death, destruction, displacement, starvation, terror, division and destitution on a massive scale," he said at U.N. headquarters in New York.

"Millions are facing extreme hunger, and the World Food Programme (WFP) had to cut rations in half due to the lack of funds. Further cuts are looming. This is a tragedy," he added.

Across Yemen, 2.2 million children are acutely malnourished.

The United Nations on Wednesday received only $1.3 billion in pledges toward a $4.27 billion aid plan for the country, where the humanitarian drive had seen funding dry up even before global attention turned to the conflict in Ukraine.

"We hoped for more and it is a disappointment that we weren't able as yet to get pledges from some we thought we might hear from," U.N. aid chief Martin Griffiths told a one-day pledging event co-hosted by Sweden and Switzerland.

He said a second pledging drive for Yemen, where millions face hunger, may be considered in a few months to "at a minimum reach levels of funding we saw last year," when donors gave $2.3 billion.

About two-thirds of the U.N.'s programs have been completely shuttered or cut down amid a funding shortfall and escalating hostilities. The aid cuts have resulted in food rations being reduced for 8 million people and reductions in safe water supplies and gender-based services, according to the U.N.

Hollywood actress Angelina Jolie, a United Nations High Commissioner for Refugees (UNHCR) special envoy, visited Yemen last week to draw attention to the humanitarian crisis in which more than 17 million people require food aid.

"It is heart-breaking. It is infuriating," said Jolie. "There is nothing more important for Yemen than to end the conflict."

Speaking at a U.N. pledging event, Guterres said: "We are ready to keep supporting the Yemeni people – but we cannot do it alone. We need your help.

"As a matter of moral responsibility, of human decency and compassion, of international solidarity, and of life and death, we must support the people of Yemen now."