Talks between Russia, Ukraine, Turkey and UN officials on resuming Black Sea exports of Ukraine grain resulted in an agreement to form a coordination center in order to ensure the safety of routes, the Turkish defense minister said on Wednesday.

In a statement, Turkey's Defense Minister Hulusi Akar said an agreement would be signed next week when all parties meet again, adding the parties had agreed on joint controls for checking grains at harbors.

Turkey would also set up a coordination centre with Ukraine, Russia and the United Nations for grain exports, he said.

UN Secretary General Antonio Guterres said a "critical step forward" had been made toward reviving Ukrainian grain exports but cautioned that "more technical work will now be needed to materialize today's progress".

"Today is an important and substantive step, a step on the way to a comprehensive agreement". Ukraine and Russia had shown they could talk, but "for peace we still have a long way to go," Guterres told reporters in New York.

(With input from Reuters)