Three grain-loaded cargo vessels left Ukrainian ports on Tuesday, according to the centre overseeing the implementation of a deal brokered by Turkey and the UN.
"The movement of these vessels has been agreed by the Ukrainian, Turkish and UN delegations. The Russian delegation has been informed," the Istanbul-based International Coordination Centre told French news agency AFP.
The ships are the latest to sail from Ukraine after Russia pulled out of a July agreement that allowed vital grain exports to leave Ukraine with the aim of alleviating global food shortages.
At least 10 ships sailed from Ukraine's ports on Monday, without incident.
Moscow said it was withdrawing from the export deal after it blamed Ukraine for drone attacks on its fleet in the Black Sea.
The agreement – which established a safe corridor through which vessels could travel to Istanbul for inspection – had allowed more than 9.5 million tonnes of Ukrainian grain to be exported.
The accord is due to be renewed on 19 November.
Russia on Monday said it cannot guarantee the safety of navigation, deeming the deal as "hardly feasible" without its participation.
Turkish President Recep Tayyip Erdogan is to speak with his Russian and Ukrainian counterparts in the coming days to pursue efforts to keep the agreement in force despite Russia's hesitations.
Hunger games
Maritime grain exports from Ukraine were halted last Saturday, when Russia suspended participation in the agreement which had been allowing shipments from Black Sea ports to Turkey. Moscow blames drone attacks on its vessels in Crimea for the suspension.
Last weekend, the EU urged Russia to reverse its decision.
Dmytro Kuleba, Ukraine's foreign minister, claimed on Twitter that Russia was blocking two million tons of grain on 176 vessels already at sea. He said that the cargo was enough to feed seven million people.
Kuleba accused Moscow of having planned to resume its hunger games in advance and said the Black Sea drone attacks were 220 kilometres away from the grain corridor.
Ukrainian President Volodymyr Zelensky called the Russian move an absolutely transparent intention to return the threat of large-scale famine to Africa and Asia.
Stephane Dujarric, spokesman for the UN secretary-general, said: "It is vital that all parties refrain from any action that would imperil the Black Sea Grain Initiative which is a critical humanitarian effort."
