"We must act now, to save lives", UN Secretary General Antonio Guterres told the conference in Geneva.
Earlier at the conference Mr Guterres said Yemen needed massive funds to avert starvation and that the country's warring parties must ensure humanitarian aid can be delivered.
"The world needs to ramp up aid to Yemen at this critical moment, when millions of people are at risk of dying of hunger", said NRC Secretary General Jan Egeland.
For one, Yemen, tucked away in the corner of the Arabian Peninsula, seems very far away to people in the West compared to a place like Syria, which is situated on the Mediterranean and where millions have fled into neighboring countries and regions.
The top United Nations humanitarian official has called for Gulf countries to help avert mass starvation in Yemen, where two years of war have left millions at risk of famine.
According to United Nations officials, almost two-thirds of the Yemeni population - approximately 19 million people - are in need of emergency assistance.
Oxfam is also calling on donors and global agencies to return to the country and to increase their efforts, to respond to this massive humanitarian crisis before it is too late.
United Nations officials say a feared Saudi-led attack on the port would displace up to 500,000 people and require additional humanitarian aid of up to 85 million dollars (£66 million).
"Only 15 percent has been met until the present moment", he said at a fundraising conference in Geneva.
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"That is why we basically need to make sure that there is unhindered access for all humanitarian actors to reach all the people in need, everybody in need, and everywhere inside Yemen", he said.
Children especially are bearing the brunt of the crisis. "We see the impact of restrictions on the movement of goods and medicines from within the country", Robert Mardini, the regional director of the International Committee of the Red Cross (ICRC) for the Middle East, said in a statement issued Tuesday.
The request was made at the commencement of a donor session conference in Geneva.
The food crisis in Yemen has been exacerbated by the ongoing conflict between Houthi rebels controlling Sana'a allied with former president Ali Abdullah Saleh, who led the country from 1990 to 2012, and forces loyal to ousted president Abdu Rabbu Mansour Hadi.
"While aid will provide welcome relief, it will not heal the wounds of war that are the cause of Yemen's misery", said Sajjad Mohamed Sajjad, Oxfam's country director in Yemen.
"We are in a race against time", he added.
Yemen imports 90 per cent of its food, 70 per cent of which passes through the strategic Red Sea port of Hodeidah, now held by the Houthi militias and their allies, forces loyal to former president Ali Abdullah Saleh.
Western governments were attending the event "while they continue to sell billions of dollars worth of weapons and military equipment to parties to the conflict", it said.
Cappelaere said UNICEF and other aid groups have called on all parties to keep the port and other entry points, such as the Sanaa airport, open on a daily basis to bring in much-needed supplies.