Istanbul, 7 June 2022 (dpa/MIA) - Turkey has seen "significant progress" in negotiations with Ukraine, Russia and the United Nations for a possible deal to allow grain exports from Ukraine's Black Sea ports, according to Turkish Defence Minister Hulusi Akar on Tuesday. Akar's remarks, quoted by state news agency Anadolu, come hours ahead of Russian Foreign Minister Sergei Lavrov's planned visit to Ankara. Turkey has been trying to act as a mediator in Russia's war on Ukraine. Opening a so-called corridor for Ukrainian grain shipments through Turkish straits into the Mediterranean is among the topics Lavrov is expected to discuss with his Turkish counterpart Mevlüt Çavuşoğlu, state broadcaster TRT reported on Monday. The future of grain deliveries from Ukrainian ports, currently on hold due to the Russian invasion and fear of naval mines, remains a huge issue of concern amid rising global food prices. Turkey has proposed establishing a centre in Istanbul to coordinate and monitor de-mining efforts and shipments to distribute as many as 20 million tons of grain to global markets, TRT said. Talks continue on technical issues including "how to clear mines, who will do it, how the corridor will be created and who will escort [the ships]," Akar said, according to Anadolu. The parties are willing to resolve the issue but mutual trust remains a sticking point, Akar said. "Everybody wants to be sure of certain things. We are working to establish such trust." Ukraine demands security guarantees while Russia raised concerns over possible arms shipments to Ukraine, according to TRT.