World food prices hit an all-time high in March as Russia's invasion of Ukraine sent "shocks" through markets for staple grains and vegetable oils, the UN's Food and Agriculture Organisation said Friday.

The disruption in export flows resulting from the February 24 invasion and international sanctions against Russia has spurred fears of a global hunger crisis, especially across the Middle East and Africa, where the knock-on effects are already playing out.

Russia and Ukraine, with vast grain-growing regions that are among the world's main breadbaskets, account for a huge share of the globe's exports in several major commodities such as wheat, vegetable oil and corn.

"World food commodity prices made a significant leap in March to reach their highest levels ever, as war in the Black Sea region spread shocks through markets for staple grains and vegetable oils," the FAO said in a statement.

The FAO's food price index, which had already reported a record in February, surged by 12.6% last month, "making a giant leap to a new highest level since its inception in 1990", the UN agency said.

The index, a measure of the monthly change in international prices of a basket of food commodities, averaged 159.3 points in March.