"In Russian-occupied Ukraine, the Kremlin's army is confiscating grain stocks and machinery," von der Leyen told global leaders gathered at the annual World Economic Forum in Davos, Switzerland.
She added that "Russian warships in the Black Sea are blockading Ukrainian ships full of wheat and sunflower seeds" to prevent Ukraine from exporting its grain to international markets.
She called for "global cooperation" as "the antidote to Russia's blackmail," the Reuters news agency reported.
Von der Leyen has previously accused Russia of using energy supplies "as an instrument of blackmail."
Polish President Andrzej Duda said in Davos on Tuesday that the war in Ukraine could cause food shortages in North Africa, potentially resulting in mass migration to Europe.
"If it turns out that there is hunger in North Africa... both Spain and the whole of southern Europe will have a huge migration problem," Andrzej Duda warned during a panel discussion in the Swiss Alpine resort.
"Today we should focus on Ukraine being able to export its grain," he said.
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Source: Reuters, IAR, PAP