Russian officials have shrugged off such claims, saying they have not obtained hard evidence that he was poisoned with Novichok, a Soviet-developed chemical weapon.

In a report published this week by the medical journal The Lancet, the Charite team said a Novichok poison was detected in Navalny’s bloodstream after his admission to the hospital in August.

“A laboratory of the German armed forces designated by the Organization for the Prohibition of Chemical Weapons identified an organophosphorus nerve agent from the Novichok group in blood samples collected immediately after the patient’s admission to Charite,” the report said.

Navalny, 44, narrowly survived the poisoning, according to the German hospital team. “His good health status before the poisoning probably favoured his recovery,” the report said.

Navalny became violently ill while on a domestic flight in Russia on August 20 and was initially treated at a hospital in the Siberian city of Omsk for two days before being medically evacuated to Berlin.