The German government says tests performed on samples taken from Russian opposition leader Alexei Navalny showed the presence of the Soviet-era nerve agent Novichok.
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 a 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 that he had been poisoned.
Chancellor Angela Merkel's spokesman, Steffen Seibert, said in a statement Wednesday that testing by a special German military laboratory had shown proof of "a chemical nerve agent from the Novichok group." Novichok, a Soviet-era nerve agent, was used to poison former Russian spy Sergei Skripal and his daughter in Britain.
It is a cholinesterase inhibitor, part of the class of substances that doctors at the Charite initially identied in Navalny.