President Vladimir Putin has authorised Armenian investment fund Balchug Capital's purchase of Goldman Sachs' unit in Russia, a government decree published on Friday showed, potentially paving the way for the U.S. bank to fully withdraw from Russia. Moscow has steadily tightened restrictions on foreign asset sales since the start of the conflict in Ukraine, with banks requiring Putin's approval for any deal. A source confirmed Goldman Sachs had entered into a binding agreement to dispose of its Russian subsidiary, subject to various conditions.