The U.N. food chief warned on Tuesday that the war in Ukraine was threatening to devastate the World Food Programme's efforts to feed some 125 million people globally because Ukraine had gone "from the breadbasket of the world to breadlines."

"It's not just decimating dynamically Ukraine and the region, but it will have global context impact beyond anything we've seen since World War Two," WFP Executive Director David Beasley told the 15-member United Nations Security Council.

Beasley said 50% of the grain bought by the WFP, the food-assistance branch of the United Nations, comes from Ukraine, "so you can only assume the devastation that this is going to have on our operations alone."

"The farmers are on the frontlines," he said.

Beasley added that the crisis was compounded by a lack of fertilizer products coming from Belarus and Russia.

"If you don't put fertilizer on the crops, your yield will be at least 50% diminished. So we're looking at what could be a catastrophe on top of a catastrophe in the months ahead," he told the council.

Before Russia's Feb. 24 invasion of neighboring Ukraine, Beasley said the WFP was already struggling with high fuel and food prices and shipping costs that was forcing it to cut rations for millions of people in places like Yemen.

Beasley warned if the conflict in Ukraine was not ended, "the world will pay a mighty price and the last thing we want to be doing as the World Food Programme is taking food from hungry children to give to starving children."

Russia's U.N. Ambassador Vassily Nebenzia rejected accusations that Moscow's actions in Ukraine had caused the "serious turbulence" in the global food market, instead blaming Western sanctions on Russia.

Russia calls its invasion a "special military operation" that aims to destroy Ukraine's military infrastructure. The 193-member U.N. General Assembly has overwhelmingly deplored Russia's "aggression" and demanded it withdraw its troops.

U.S. Deputy Secretary of State Wendy Sherman told the council sanctions were not fueling the global food crisis.

"The responsibility for waging war on Ukraine – and for the war's effects on global food security – falls solely on President Putin," Sherman said.