BERLIN — The German government said on Wednesday that the Russian opposition leader Aleksei A. Navalny, who is being treated in Germany, had been poisoned with the nerve agent Novichok, and demanded an explanation from Moscow.
Sergei V. Skripal, a former Soviet spy, and his daughter were poisoned with a nerve agent from the Novichok group in a 2018 attack in Britain that Western nations have attributed to Russia.
Toxicology tests carried out by a German Army laboratory revealed the “doubtless presence of a chemical nerve agent of the Novichok group” in the system of Mr. Navalny, who was flown to Germany on Aug. 22 after he collapsed while on a flight from Siberia to Moscow.
“The German government condemns this attack in the strongest possible terms,” Steffen Seibert, a spokesman for Chancellor Angela Merkel, said in a statement. “The Russian government is urgently requested to explain what happened.”
The Kremlin said it was not informed of Germany’s findings before the announcement, the Russian state news outlet Tass reported. The German Foreign Ministry will inform the Russian ambassador of the findings, Mr. Seibert said.