Ukraine's ambassador to Ankara on Friday accused Russia of "stealing" and sending Ukrainian grain abroad to countries including Turkey.
"Russia shamelessly steals Ukrainian grain and sends it overseas from Crimea, including to Turkey," said Kyiv's envoy in Ankara, Vasyl Bodna.
"We have asked for Turkey's help to resolve the issue," he added in a message on Twitter.
Ukraine was a major exporter of wheat and sunflower oil before Russia's invasion on February 24, AFP said.
Ankara has maintained a delicate balancing act with Kyiv and Moscow.
NATO member Turkey has delivered combat drones to Ukraine and sought to act as mediator in the conflict, but has refrained from slapping sanctions on Russia on which it relies for grain and energy.
Ankara has also offered, at the request of the United Nations, to help secure maritime corridors for the export of Ukrainian grain.
Russian Foreign Minister Sergei Lavrov will be in Turkey on Wednesday to discuss the issue.
Food prices have soared since the war began, with countries in Africa and the Middle East particularly at risk since grain cannot be delivered because of the Russian navy blockade of Ukrainian ports in the Black Sea.