The most senior US diplomat at the UN condemned the Security Council for failing to act over atrocities and a growing famine in Ethiopia's Tigray region, asking "do African lives not matter?"
"The Security Council's failings on Tigray are unacceptable," Linda Thomas-Greenfield, ambassador to the UN, said at a virtual event organised by the US and the European Union.
She said it was "time for the Ethiopian government to respond responsibly to requests for humanitarian access".
Thomas-Greenfield made the comments as the UN and aid agencies said more than 350,000 people faced extreme food shortages in Tigray, renewing memories of a famine that left a million people dead in the 1980s.
That is the largest number of people classified at 5 on the Integrated Food Security Phase Classification (IPC) famine scale - the highest level possible - in a single country for a decade.
A further 2 million people in Tigray have been classified at 4 and could slide into starvation.
The findings were presented at a meeting on Monday between 18 UN and non-UN organisations, chaired by Mark Lowcock, the UN's humanitarian chief.
He said: "There is famine now. This is going to get a lot worse."
The Ethiopian government has rejected the IPC Phase 5 classification.
"We don't have any food shortages," said Mituku Kassa, of the National Disaster Prevention and Preparedness Committee.
In the past decade famine has only been declared in Somalia in 2011 and South Sudan in 2017.
Ethiopia's government has been waging a bloody war with leaders of the Tigray region since November, leading to the displacement of more than two million people and reports of genocide and war crimes.
Calls for Ethiopia to declare a ceasefire and allow humanitarian access to the mountainous region of around seven million people have so far gone unheeded.