The EU called on Moscow Thursday to cooperate on an international probe into the poisoning of Russian opposition leader Alexei Navalny and said it would not rule out sanctions. "The European Union calls upon the Russian Federation to fully cooperate with the Organisation for the Prohibition of Chemical Weapons (OPCW) to ensure an impartial international investigation," Brussels said in a statement, adding it "reserves the right to take appropriate actions, including through restrictive measures." clp/fjb/spm/pvh