More than 20 million tons of Ukrainian grain are stuck in silos at the Black Sea port of Odesa and dozens of ships have been stranded due to Russia's blockade, part of what Moscow calls its "special military operation" in Ukraine.
Kyiv and the West say the effective blockade is an unjustified war of aggression, using food as a weapon.
Ukrainian Foreign Minister Dmytro Kuleba told Spanish newspaper El Pais ahead of the talks in Istanbul between Ukrainian, Russian, Turkish and U.N. officials that Kyiv believed it was now very close to striking a deal for exports to resume.
"We are two steps away from a deal with Russia. We are in the final phase and now everything depends on Russia," it quoted him as saying. Other participants in the negotiations were more cautious, saying much remained to be agreed.
The movement of grain is acutely important to Africa, where a combination of drought and war-triggered food shortages is creating hunger, even starvation. The African Union has called repeatedly for parties to the conflict to allow ships to move through the Black Sea.
