Rishi Sunak said “no parent should ever have to watch their child starve” as he opened the World Summit on Food Security in London on Monday.
The Prime Minister also published a White Paper outlining the Government's long-term approach to international development more broadly to 2030.
Speaking at the gathering at Lancaster House, Mr Sunak announced a new virtual hub to connect UK scientists with global research initiatives aimed at developing climate and disease resistant crops.
He said: “In a world of plenty, no one should die from lack of food and no parent should ever have to watch their child starve.”
On the Israel-Hamas conflict, Mr Sunak reiterated his position that Israel has the right to defend itself, but added: “It must also act within the framework of international humanitarian law.
“The situation on the ground is truly dire and getting worse.”
He said the UK was pushing for meaningful humanitarian pauses, “because the suffering of innocent citizens must end”. Mr Sunak will use a separate speech in London to update the public on the state of the economy ahead of Wednesday's autumn statement.
The UK is co-hosting the food summit in London with Somalia, the United Arab Emirates, the Children's Investment Fund (CIFF) and the Bill & Melinda Gates Foundation.
The Prime Minister said the White Paper would demonstrate the UK's new approach to development, “going further to help the poorest and support those suffering from humanitarian crises”, leading not just “with strength, but with compassion” and harnessing Britain's expertise in development and science.
“We live in a dangerous world, in an era of increasing threats, strategic competition and conflict. Now, many of these challenges, such as the war in Ukraine, have a direct impact on the world's poorest.”
The UK is changing its approach “to deliver in a changing world”, Mr Sunak said. The Prime Minister also announced additional support to the international child nutrition fund.
UK support for child malnutrition will be matched pound for pound by the amount worst-hit countries such as Uganda, Ethiopia and Senegal invest from their own resources to tackle the issue, the Office said Foreign, Commonwealth and Development (FCDO).
Up to £100 million in humanitarian funding is being released to countries most affected by food insecurity, such as Ethiopia, Sudan, South Sudan and Afghanistan, and to countries affected by climate-related weather events, such as Malawi, FCDO reported.
Lisa Nandy, Labour's shadow minister for international development, said: “Rishi Sunak is the chancellor who abolished DFID (Department for International Development) and slashed aid spending, costing lives and destroying Britain's reputation as the gold standard in international development. . Asking him to repair the damage is like asking the arsonist to put out the fire.
“On nutrition alone, his decisions helped reduce food rations for 440,000 Kenyan refugees to 52% of basic food needs.”
International Development Minister Andrew Mitchell said: “Many children go to bed hungry and malnourished.
“At this summit, the UK and its partners will be united in our determination to change that. Cutting-edge science and innovative partnerships will help Britain create a healthier, safer and more prosperous world for us all.
“Today we will launch the UK's International Development White Paper, which will set out our long-term vision for tackling critical global challenges, including preventing and tackling child wasting, through new partnerships and funding sources.
“The World Food Summit is a practical example of how we are already working to realize this vision.”
FCDO says the White Paper's priorities for international development include mobilizing international finance, reforming the international system, harnessing innovation and putting women and girls at the centre.
It will also set out how the UK will go beyond providing aid money and instead work with countries to tackle extreme poverty and climate change, the government said.