Photos taken by Maxar, a satellite imagery service, have shown two Russia-flagged ships docking at Sevastopol in Crimea, which Russia annexed in 2014.
The Matros Pozynich and Matros Koshka vessels are seen docking next to what appear to be grain silos transferring the grain on to the deck via conveyor belts.
Both ships then left the port and are now in the Aegean Sea and the Black Sea, according to shipping monitors.
According to CNN, Ukrainian officials and industry sources have said that Russian forces are stealing grain from areas in their control and moving it to Crimea in the south.
It is at least the second time that the Matros Pozynich appears to have stolen Ukrainian grain, CNN reported, as earlier this month it was spotted taking grain from the Black Sea to the Mediterranean.
The vessel eventually docked at a port in Syria, which is led by the dictator Bashar al-Assad and is one of Russia’s closest military allies.
Mykola Solsky, Ukraine’s food minister, told CNN the grain is being “sent in an organised manner in the direction of Crimea”.
He added: “This is a big business that is supervised by people of the highest level.”
In addition to stealing grain, Russia has blockaded Ukrainian ports, which has left around 22 million tonnes of grain stuck in silos, severely affecting global food supplies.
According to some estimates, the world has around 10 weeks of stockpiled wheat left, while the British government has warned that vulnerable countries such as Somalia could face a worse crisis than the 2011 famine.
Meanwhile, Russia’s offensive in the Donbas yesterday made significant gains, with Ukrainian officials saying the “fate of the country” could be decided in the ongoing battles.
Moscow’s troops were close to encircling the neighbouring cities of Severodonetsk and Lyschansk, whose capture would give them control of half of the eastern region.
The two cities straddle the Siversky Donets river and Ukrainian forces are heavily dug-in there after resisting separatists in the war of 2014.
Amid heavy shelling across the eastern front, Russian forces seized three towns in the Donetsk region of the Donbas, according to its Ukrainian governor. There were also unconfirmed reports they had cut off the road through which Kyiv has been resupplying its fighters in Severodonetsk, which is Ukraine’s last stronghold in Luhansk, the other half of the Donbas.
“Now we are observing the most active phase of the full-scale aggression which Russia unfolded against our country,” said Oleksandr Motuzyanyk, a spokesman for the Ukrainian ministry of d efence.
“The situation on the eastern front is extremely difficult, because the fate of this country is perhaps being decided there right now.”
Russian forces yesterday also captured Svitlodarsk, south-west of Bakhmut, after Ukrainian forces retreated from their defences there.
Yesterday evening, a Russian thrust from Popasna to the east appeared to have reached the T1302 highway from Bakhmut to Severodonetsk.
Capturing the so-called “life road” would give the Ukrainian troops no escape route out of Severodonetsk, leaving them facing the same fate as the defenders of Mariupol.
The fall of the cities would place the entire Luhansk region under Russian occupation and allow Vladimir Putin to claim partial success in his month-old Donbas offensive.