Ukraine, the United Nations and Turkey hailed progress at talks in Istanbul that aim to resume Black Sea grain exports blocked by Russia and ease the risk of starvation faced by millions, but an end to the war remained far off as heavy shelling continued.

Turkey's Defense Minister Hulusi Akar said on Wednesday an agreement would be signed next week. Ankara will ensure the safety of shipments in transit and the parties will jointly check grain cargoes in ports, he added.

But U.N. chief Antonio Guterres said more work was needed before a deal was finalized.