Russia will discuss the possibility of holding a prisoner exchange with Ukraine once prisoners who surrendered have been convicted Russia is ready to provide a humanitarian corridor for vessels carrying food to leave Ukraine, in return for the lifting of some sanctions, the Interfax news agency cited Russian Deputy Foreign Minister Andrei Rudenko as saying on Wednesday. Ukraine’s Black Sea ports have been blocked since Russia sent thousands of troops into Ukraine on Feb. 24 and more than 20 million tons of grain are stuck in silos in the country. Russia and Ukraine account for nearly a third of global wheat supplies and the lack of significant grain exports from Ukraine ports is contributing to a growing global food crisis. Ukraine is also a major exporter of corn and sunflower oil. Western powers have been discussing the idea of setting up “safe corridors” for grain exports from Ukraine’s ports, adding that any such corridor would need Russian consent. “We have repeatedly stated on this point that a solution to the food problem requires a comprehensive approach, including the lifting of sanctions that have been imposed on Russian exports and financial transactions,” Rudenko was quoted as saying. “And it also requires the demining by the Ukrainian side of all ports where ships are anchored. Russia is ready to provide the necessary humanitarian passage, which it does every day.” Russia is in touch with the United Nations on the issue, Rudenko was quoted as saying by another news agency, RIA. Russia and Ukraine accuse each other of planting drifting mines in the Black Sea. Rudenko was also quoted by Interfax as saying that possible escort by Western ships of Ukraine’s vessels carrying grain would “seriously exacerbate the situation in the Black Sea.” Britain said on Tuesday there are no plans to send British warships to help get food exports out of the blockaded Ukrainian port of Odesa. Odesa, on the Black Sea, is Ukraine’s main deep-water port. On the shallow-water Azov Sea, Russia’s defense ministry said on Wednesday that the port of Mariupol, the Ukrainian city which was taken by Russia, is operating normally after Russian forces completed removing mines from there.