Istanbul (AFP) – Russia and Ukraine on Wednesday made substantive progress in their first direct talks since March on a deal to relieve a global food crisis caused by blocked Black Sea grain exports. The high-stakes meeting involving UN and Turkish officials in Istanbul broke up after slightly more than three hours with an agreement to meet again in Turkey next week. Ukraine is a vital exporter of wheat and grains such as barley and maize, and has supplied nearly half of all the sunflower oil traded on global markets, but shipments have been disrupted since Russia invaded its neighbour in Febr…