The presidents of Ukraine and Türkiye will discuss on Friday the potential extension of the Black Sea grain deal and a possible prisoner exchange between Moscow and Kyiv, a senior Turkish official said ahead of the talks. Ukrainian President Volodymyr Zelenskiy will meet Turkish leader Tayyip Erdogan in Istanbul following visits to Bulgaria and the Czech Republic, part of a tour of some NATO capitals aimed at encouraging them to take concrete steps at a summit next week towards granting Kyiv membership of the alliance, Reuters said.