Ukraine has accused Moscow of stealing 400,000 tonnes of grain in regions Russian troops are occupying.
Vladimir Putin ordered his troops to invade Ukraine in February but, after failing to take over the capital of Kyiv, ordered a new offensive in the south east of the county in a bid to fully take over the Donbas region.
Ukraine is a major exporter of grain, and sold 44.7 million tonnes abroad in 2020/21- making it the world's fourth-largest supplier.
But since Russia invaded, the volume of exports has fallen sharply, and the United Nations has warned 1.7 billion people worldwide may face poverty and hunger due to food disruptions as a result of the war.
According to the Kyiv Independent, Ukraine has now accused Russia of moving hundreds of thousands of tonnes of grain, threatening the supply chain of future harvests.
The grain has reportedly been taken from the areas of Zaporizhia, Kherson, Donetsk and Luhansk in the south-east.
According to the Kyiv Independent, deputy minister of agrarian policy and food Taras Vysotsky told local media: "About 1.3 million tons of grain were left in the temporarily occupied territories.
"These are, first of all, needed to ensure daily food security and the nutrition of Ukrainians living there, and the necessary spring field work in terms of spring crops. There were no strategic reserves there…
"We already have confirmation from each region - Zaporizhia region, Kherson region, Donetsk, Luhansk, from each of about 100 thousand tonnes of grain has been exported."
Vysotsky warned that the regions may experience famine as a result.
It is believed the haul accounts for one-third of all reserves in those regions.
There are also accusations that Russia is disrupting exports by blocking ships leaving the Black Sea ports. The UN has previously warned such a situation could trigger a food crisis that will affect Europe, Asia and Africa including, in some parts of the world, famine and starvation.
It has recorded food price inflation rate of 12% – the highest level since 1990 - since the invasion.
Watch: EU eyes Russian oil import ban as Moscow strikes western Ukraine
Ukrainian President Volodymyr Zelenskyy said on Monday: "Russia does not let ships come in or go out, it is controlling the Black Sea. Russia wants to completely block our country's economy.
In April, Russian soldiers were accused of taking 61 tonnes of wheat from an agricultural enterprise in the Zaporizhzhia region.
The prosecutor general said in a statement at the time that soldiers threatened workers to take the precious resource, and that a criminal investigation had been opened.
The Kremlin said it had no information on the matter with spokesperson Dmitry Peskov saying via the Telegram messaging app: "No. We do not know where this information comes from."
The Ukrainian Foreign Ministry said of the claims that it "strongly condemns the criminal actions of the Russian Federation in the so-called expropriation of crops from farmers in the Kherson region" of southern Ukraine.
"The looting of grain from the Kherson region, as well as the blocking of shipments from Ukrainian ports and the mining of shipping lanes, threaten the world's food security," it said.
"We demand that Russia stop the illegal theft of grain, unblock Ukrainian ports, restore freedom of navigation and allow the passage of merchant ships."
Echoes of the past
This is not the first time Ukraine has been faced with a devastating famine.
In 1932-33, the "Holodomor", also known as the "Terror Famine", was part of a wider Soviet Union food crisis in which millions of Ukrainians died.
The term Holodomor comes from the Ukrainian words "holod", meaning hunger, and "moryty", to kill, and in Ukraine the tragedy is seen as an act of mass murder by the Soviet leaders of the time.
According to some experts, the famine was a consequence of the collectivisation of agriculture under the Stalin regime.
However, in the Ukraine, the famine is widely regarded as a deliberate attempt by Stalin to destroy Ukrainian freedoms and kill off an independence movement.
Either way, the famine devastated the social fabric of the countryside, where the Ukrainian vernacular was spoken and national identity had been flourishing.
Recognition of the full extent of the Holodomor and implicating Soviet leadership for the deaths remains an important issue in Ukraine to this day, with the country’s leaders long fighting for global recognition of the Holodomor and its impact on modern Ukraine.
Fifteen countries including the United States and Canada have made official declarations calling it a genocide.
Just as the the Soviet government of the day denied that there were any decisions that explicitly deprived Ukraine of food – noting that the famine affected the entire country – so too do present-day Russian leaders refuse to acknowledge culpability.
This is interpreted in the Ukraine has an additional attempt to downplay Ukrainian identity.
Reuters contributed to this report