Moscow said on Thursday that sanctions on Russia would have to be reviewed if it were to heed a U.N. appeal to open access to Ukraine's Black Sea ports so that grain could be exported, according to an Interfax news agency report. Read full storyUkraine, one of the world's biggest grain producers, used to export most of its goods through its seaports, but since Russia sent troops into Ukraine, it has been forced to export by train or via its small Danube River ports…