International food and feed prices could rise by up to 20% as a result of the conflict in Ukraine, triggering a jump in global malnourishment, the United Nations food agency said on Friday.

The Rome-based Food and Agriculture Organization (FAO) said it was not clear whether Ukraine would be able to harvest crops if the war dragged on, while uncertainty also surrounded the prospects for Russian exports in the coming year.

FAO said Russia was the world’s largest exporter of wheat and Ukraine was the fifth largest. Together, they provide 19% of the world's barley supply, 14% of wheat, and 4% of maize, making up more than one-third of global cereal exports.

Russia is also a world leader in fertilizer exports.

“The likely disruptions to agricultural activities of these two major exporters of staple commodities could seriously escalate food insecurity globally,” FAO Director General Qu Dongyu said in a statement.

FAO’s food price index hit a record high in February, and looks certain to climb further still in the months ahead as the consequences of the conflict reverberate around the world.

FAO said only part of the expected shortfall in exports from Russia and Ukraine could be met by other countries.

“Worryingly, the resulting global supply gap could push up international food and feed prices by 8 to 22% above their already elevated levels,” it said.

Between 20% and 30% of fields used to grow winter cereals, maize and sunflower in Ukraine will not be planted or will remain unharvested during the 2022/23 season, FAO predicted.

FAO said 50 countries, including many of the least developed nations, depend on Russia and Ukraine for 30% or more of their wheat supplies, leaving them especially vulnerable.

“The global number of undernourished people could increase by 8 to 13 million people in 2022/23,” FAO said.

The most pronounced rises would be seen in the Asia-Pacific region followed by sub-Saharan Africa, the Near East and North Africa.

FAO urged other countries not to impose export restrictions on their own produce. “They exacerbate price volatility, limit the buffer capacity of the global market, and have negative impacts over the medium term,” the agency said.

A number of countries worldwide have announced food export restrictions or are considering bans to protect their domestic supplies after Russia's invasion of Ukraine, which Moscow terms a “special operation”.