The head of the United Nations World Food Programme has warned that the Russian invasion of Ukraine is threatening to cause a severe food crisis in the world.

WFP Executive Director David Beasley made the remarks through a video link during a UN Security Council session on Tuesday.

Beasley noted that the WFP was already struggling with soaring food prices and shipping costs, forcing the agency to cut rations for millions of people including children around the world.

The WFP chief said that the invasion is threatening WFP's efforts because Ukraine had gone "from the breadbasket of the world to breadlines."

He went on to say, "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."

The WFP says Ukraine and Russia together supply 30 percent of wheat and 20 percent of maize to global markets.