GENEVA — Ukraine’s food supply chain is “falling apart” amid the Russian invasion, and the disruption of food supplies within the country is threatening crucial exports of grain that could undermine global food security, the United Nations said Friday.

The World Food Program said it has mobilized food supplies for around 3 million people caught in areas of heavy fighting, but that it will need $590 million to fund its operation for four months.

“The consequences of this conflict in Ukraine are radiating outwards, triggering a wave of collateral hunger across the globe,” Jakob Kern, the organization’s operations director, told reporters. “Ukraine is a catastrophe compounding what is already a year of catastrophic hunger.”

Russia and Ukraine account for nearly 30% of the world’s wheat trade, Kern said, and the interruption of those exports is driving up prices to levels that will be beyond the reach of millions of poor people.

The price of wheat has jumped nearly a quarter since Feb. 21, Kern said. That increase has pushed the World Food Program’s monthly food bill up by about $70 million, a sum that would allow it to support 4 million people.

“That’s 4 million people less receiving food,” he said.

In particular, he noted that Lebanon, which gets more than 60% of its wheat from Ukraine, is among the Middle Eastern countries that are heavily dependent on Ukrainian grain supplies and stand to be heavily affected by the fallout of the war.

This article originally appeared in The New York Times.