Ships left Ukrainian ports carrying grain on Monday, suggesting Moscow had stopped short of reimposing a blockade that could have threatened world food supplies.
Over the weekend, Russia pulled out of the UN-brokered deal to export Ukrainian grain across the Black Sea, increasing prices and raising the spectre of hunger once again.
The continuation of shipments from southern Ukraine suggests Moscow has not reinstated the naval blockade, which previously left hundreds of thousands of tonnes of grain bound for the developing world languishing in silos.
"Civilian cargo ships can never be a military target or held hostage. The food must flow," tweeted Amir Abdullah, the UN official who coordinates the grain programme, on Monday.
Ukraine confirmed that 12 ships had set sail, shortly afterwards.
They carried an estimated 354,500 tonnes of grain -- the most in a day since the deal between Russia and Ukraine was struck in July.
But shipments could be interrupted again if insurers stop underwriting them, reports Reuters.
Chris McGill, at Lloyd’s of London insurer Ascot, which has insured many of the shipments, told reporters his company was pausing new cover for shipments from Monday "until we better understand the situation".
Moscow said it was forced to pull out of the agreement after blasts it blamed on Ukraine damaged Russian navy ships in Crimea on Saturday.
Kyiv neither confirmed nor denied its involvement.
Ukraine and Russia are both among the world's largest exporters of food.
For the last three months, the UN-backed deal lifted a Russian de facto blockade on Ukraine in place since the start of the war, allowing shipments to Africa and the Middle East.
Moscow's pull-out of the deal on Saturday sent global wheat prices
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