Some 13 million people are on the brink of starvation in war-torn Yemen, the UN has warned.
It says the country is facing the worst famine for a century and that there are just three months left to avoid catastrophe.
Yemen is in the grip of a civil war that began three years ago with air strikes by Saudi Arabia contributing to the humanitarian crisis.
Lise Grande, the UN's humanitarian co-ordinator for Yemen, told the BBC: "I think many of us felt as we went into the 21st century that is was unthinkable that we could see a famine like we saw in Ethiopia, that we saw in Bengal, that we saw in parts of the Soviet Union, that was just unacceptable.
"Many of us had the confidence that that would never happen again and yet the reality is that in Yemen that is precisely what we are looking at.
"We predict that we could be looking at 12 to 13 million innocent civilians who are at risk of dying from the lack of food."
When asked if the world should be ashamed, she responded: 'Yes. There's no question we should be ashamed, and we should, every day that we wake up, renew our commitment to do everything possible to help the people that are suffering and end the conflict."
The United Nations and humanitarian workers also condemned an airstrike by the Saudi-led coalition targeting Yemen's Shi'ite rebels that reportedly killed at least 15 civilians near the port city of Hodeida.