KYIV: Ukraine has sent Russia an offer suggesting they both halt attacks on civilian targets in the Black Sea, a source said, as both countries warned about threats to global food supplies following weeks of intensified strikes on vessels and ports.

The offer to suspend attacks was transmitted by Kyiv via a third party, and Ukraine was still waiting for a response, the source who is familiar with the matter told Reuters.

Both Russia and Ukraine, major players on the world agriculture market, have accused each other of intensified targeting of vessels used for agricultural exports.

Kyiv was forced to turn to alternative shipment routes after many shipowners halted stops at ports in the southern region of Odesa - primary for grain exports - wary of Russian strikes on dozens of foreign-flagged ships and port infrastructure.

Russia did not immediately comment on the matter publicly. Before the report, Deputy Russian Foreign Minister Alexander Grushko said Moscow had received no formal Black Sea ceasefire proposal.

"Recently, we have been hearing many calls for various kinds of moratoriums and truces. These ideas are being put forward through various channels, but we have not received any formal proposals," he said, according to Russia's state news agency TASS.

Euronext September wheat BL2U6 turned lower, giving up sharp earlier gains following the Reuters report about Ukraine's offer.

Turkish Foreign Minister Hakan Fidan said on Saturday that a proposal had been conveyed to Russia and Ukraine for both countries to declare a moratorium on attacks in Black Sea.

Russia's de facto blockade of Ukraine's Black Sea ports in the Odesa region has sent Ukrainian grain exports tumbling 76 per cent year-on-year so far in August, with the agricultural sector warning of vast consequences for the economy should it persist.