US Agriculture Secretary Tom Vilsack called on Russia Thursday to rapidly open Ukraine's ports to permit the export of millions of tonnes of stockpiled grain.
"They should be acting immediately to open up those ports and they should end this war," Vilsack told reporters at the United Nations.
"This is serious thing, we shouldn't be using food as a weapon," he said.
The United Nations has been deep in talks between Moscow, Kyiv and Ankara for weeks on how to open up the Black Sea, where the Russian navy has created a blockade around Ukraine, to commercial cargo ships to carry the grain to global markets.
Such an agreement would also permit Russian fertilizer, now blocked by sanctions, to return to the global market.
With grain prices soaring internationally and key importers in the Middle East and Africa facing supply shortfalls, Moscow has demanded that economic sanctions on it be lifted in exchange for allowing the exports.
Vilsack said US and European sanctions do not apply to grains and fertilizers.
Addressing the ongoing talks on the issue, Vilsack said he hoped that Russia would "take this thing seriously and that they're not just doing this to create an image."
He urged Moscow "to make sure that they are negotiating in good faith about the reopening of the ports and they do so quickly. Because the need is immediate."
Vilsack said a US proposal to build silos in Poland to receive Ukrainian grain was to reduce the possibility of spoilage before the grain can transported to markets.
On Wednesday, Turkish Foreign Minister Mevlut Cavusoglu said Ankara is ready to host a four-way meeting with the United Nations, Russia and Ukraine to organize the export of grain through the Black Sea.
Under the plan, safe corridors for grain exports from Ukraine could be established without de-mining in the Black Sea, he said.
"If Russia answers positively, there will be a four-partite meeting in Istanbul," Cavusoglu said.
There was no immediate comment from Moscow.