The Kremlin is believed to be dismantling infrastructure needed for food production and blocking ports that are vital in shipping cereals out of the country, which is known as the breadbasket of Europe.
Officials fear Russia has embarked on a “deliberate policy” of disrupting food supplies, sparking a global crisis and raising the prospect of starvation in developing countries.
The Russian army has destroyed silos and other food production infrastructure in cities such as Kherson, Luhansk and Donetsk, say Western sources.
The UN estimates that 1.7 billion people in more than 100 countries are being affected by the current surge in food, energy and commodity prices.
Official figures revealed yesterday that grocery bills in the UK rose at their fastest pace for more than a decade in April, helping to drive inflation to a 40-year high of 9pc.
A Western official said: “[Russia] has exacerbated a pre-existing bad situation and created a major threat to global food security through a policy of weaponisation of global food supply.”
They added that record grocery bills have proved the “last straw” for many poor countries, and said intelligence experts are closely monitoring the situation over fears of mass unrest across Africa and the Middle East.
Sri Lanka defaulted on its debts for the first time since independence last night following weeks of protests.
It comes after Andrew Bailey, governor of the Bank of England, warned on Monday of “apocalyptic” food price rises and raised concerns about a disastrous impact on the developing world.
In Britain, the cost of cooking oils, dairy and staples such as pasta is rapidly rising, and the crisis is far more severe in countries where food accounts for a larger share of households’ costs.
Ukraine and Russia produce a quarter of global wheat exports and a fifth of corn output between them.
Fuel, fertiliser and feed prices have jumped, with Ukraine producing half of the world’s sunflower oil.
The UN warned this week that almost 25 million tons of wheat in Ukrainian warehouses are being left to rot because the supplies cannot leave the country. It also said that some grain storage had been destroyed.
It came as Moscow said yesterday that nearly 700 more Ukrainian fighters had surrendered in Mariupol, a claim yet to be confirmed by Ukraine.
Kyiv had ordered its garrison to stand down, but a pro-Russian separatist leader said commanders were still in tunnels under the Azovstal steelworks.
Yesterday, a Russian soldier pleaded guilty to killing a Ukrainian civilian in the first war crimes trial to be held since the conflict started. The hearing in a Kyiv courtroom is one of a series of trials of Russian servicemen.
Meanwhile, Turkey vetoed a Nato decision on whether to accept Finland and Sweden into the military alliance.
At a “classified” meeting of Nato ambassadors in Brussels, the Turkish representative stopped a vote on their applications, officially submitted earlier in the day, according to sources.
The meeting was called in the hope of agreeing an accelerated accession process to head off Russian threats of aggression aimed at the Nordic nations.
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