Stoltenberg said Moscow must cooperate with the international chemical weapons organization in "an impartial, international investigation" and provide information about its Novichok program
Novichok, a class of chemical weapons developed by the former Soviet Union and Russia, was used to poison former Russian double agent Sergei Skripal and his daughter
Last weekend, Navalny was transferred to the Charit hospital in Berlin, where doctors found indications of cholinesterase inhibitors in his system
Kremlin spokesman Dmitry Peskov said Monday he saw no grounds for a criminal case until the cause of the politician's condition was fully established
A lawyer by training, 44-year-old Navalny is a high-profile critic of President Vladimir Putin and the ruling political elite in Russia
Navalny, a 44-year-old politician and corruption investigator who is one of Russian President Vladimir Putin's fiercest critics, was admitted to an intensive care unit in Omsk on Thursday
The leader is a prominent critic of President Vladimir Putin