Tests performed on samples taken from Russian opposition leader Alexei Navalny showed the presence of the Soviet-era nerve agent Novichok, the German government has said. Mr Navalny, a politician and corruption investigator who is one of Russian President Vladimir Putin’s fiercest critics, fell ill on a flight back to Moscow from Siberia on August 20 and was taken to hospital in the Siberian city of Omsk after the plane made an emergency landing. He was later transferred to Berlin’s Charite hospital, where doctors last week said there were indications he had been poisoned.