By Sabine Siebold DAVOS, Switzerland (Reuters) – European Commission chief Ursula von der Leyen on Tuesday called for talks with Moscow on unlocking wheat exports that are trapped in Ukraine as a result of a Russian sea blockade. U.S. Secretary of State Antony Blinken last week accused Russia of using food as a weapon by holding “hostage” supplies for not just Ukrainians, but also millions of people around the world. Moscow rejects this allegation. “The most important (thing) is to deblock the Black Sea. This is a call on Russia,” von der Leyen told Reuters in an interview on the sidelines of …