US aid chief Samantha Power on Monday promised $1.18 billion to help avert famine in the Horn of Africa.
It also urged other nations including China to do more to fight a food crisis aggravated by Russia's invasion of Ukraine.
Power voiced alarm that the war, as well as climate change, were worsening hunger around the world, just after a decade of progress had been "obliterated" by the Covid pandemic.
"Today we are confronting something even more devastating as not only are tens of millions more people facing that grave hunger, many of them are at risk of outright starvation," she said at the Center for Strategic and International Studies.
Power, administrator of the US Agency for International Development, said the situation was especially dire in turbulent Somalia, conflict-hit Ethiopia and Kenya, the so-called Horn of Africa which is forecast to experience its fifth straight drought later this year.
Announcing a visit to the Horn of Africa this weekend, Power said that at least 1,103 children there are known to have died and some seven million other children are severely malnourished.
Power said the $1.18 billion in US aid would include emergency food -- notably sorghum, a locally used grain more readily available than wheat -- as well as a peanut-based supplement for malnourished children and veterinary services for dying livestock.
"Now we need others to do more, before a famine strikes, before millions more children find themselves on the knife's edge," she said.
Global prices of food have skyrocketed due to the war in Ukraine, a leading wheat exporter, with Russian warships blocking ports as Kyiv lays mines to avert a feared amphibious assault.
Power criticized the "sinister" policies of Russia but also pinned blame on China -- seen by the United States as a leading global competitor -- over its trade restrictions on fertilizer and "hoarding" of grain.
If China released fertilizer or grain to the global market or World Food Programme, it would "significantly relieve pressure on food and fertilizer prices and powerfully demonstrate the country's desire to be a global leader and a friend to the world's least developed economies," she said.
She also issued a tacit criticism of India, which is seen by Washington as an emerging ally but has declined to shun historic partner Russia and has imposed its own export ban on wheat.
Praising Indonesia for lifting restrictions on palm oil, Power said, "We encourage other nations to make similar moves, especially since several of the countries instituting such bans have been unwilling to criticize the Russian government's belligerence."
"Countries that have sat out this war must not sit out this global food crisis," she said.
