The United Nations has warned the conflict and economic sanctions on Russia have disrupted global food supplies, sparking fears of widespread hunger.
The European Union, the United States and more than two dozen other countries have vowed to shore up global food security in a joint statement to the World Trade Organization.
Voicing alarm at the "global effects on food security" triggered by Russia's incursion of Ukraine, they stressed on Friday "the urgency and importance of maintaining open and predictable agricultural markets and trade."
That would "ensure the continued flow of food, as well as products, services and inputs essential for agricultural and food production and supply chains," they added.
The United Nations has warned the conflict and economic sanctions on Moscow have disrupted global food supplies, sparking fears of widespread hunger.
"The bullets and bombs in Ukraine could take the global hunger crisis to levels beyond anything we've seen before," World Food Programme chief David Beasley warned back in March.
The conflict, he later told the UN Security Council, would mean "skyrocketing food, fuel and shipping costs, less food for the starving and even more people going hungry."
Russia and Ukraine, whose vast grain-growing regions are among the world's main breadbaskets, account for a huge share of the globe's exports in several major commodities, including wheat, vegetable oil and corn.
Together, they account for 30 percent of the global wheat trade.
Markets in turmoil
The conflict has sent commodity prices soaring, with the price of sunflower and colza oil shooting up 40 percent in Europe in two months.
And the turmoil in markets has deepened as some countries mull cutting exports to ensure supply at home.
Indonesia's recent decision to suspend palm oil exports in the face of domestic shortages has pushed vegetable oil prices to new highs.
There has also been speculation that India, the world's number two wheat producer hit by a record heatwave, would curb exports of the grain - something New Delhi denies.
Indonesia and India were not among the 51 WTO member states who signed Friday's statement. Large agriculture nations like Brazil and Argentina were also missing.
Pledge to work together
The document highlighted "the importance of exercising restraint in excessive stockpiling and hoarding of agricultural products affected by this crisis that are traditionally exported."
The countries pledged to work together to ensure "sufficient, safe, affordable and nutritious food" is available to everyone at all times, and vowed to keep their food and agriculture markets "open."
They warned applying measures such as "unjustified export prohibitions and restrictions on agricultural and agri-food products, increases uncertainty and can result in a spiral of price increases and further restrictions."
They said any country's measures to mitigate food security impacts should be "as least-distortive as possible" and should follow WTO rules.
And they stressed no export bans or restrictions should be imposed on food purchased by the UN's World Food Programme for humanitarian purposes.