Russian opposition politician Alexei Navalny was poisoned with a Novichok nerve agent, Germany’s government says.
It said toxicology tests at a military laboratory showed “”unequivocal proof” of an agent from the Novichok group.
Mr Navalny was airlifted to Berlin for treatment after falling ill during a flight in Russia’s Siberia region last month. He has been in a coma since.
His team says he was poisoned on President Vladimir Putin’s orders. The Kremlin has dismissed the allegation.
The German government said it condemned the attack in the strongest terms and called for Russia urgently to provide an explanation.
“It is a disturbing development that Alexei Navalny was the victim of a chemical nerve agent in Russia,” it said.
Chancellor Angela Merkel has met senior ministers to discuss the next steps, the statement said.
The Kremlin said it had not received any information from Germany that Mr Navalny had been poisoned using a Novichok nerve agent, Russia’s Tass news agency reported.
The German government said it would inform the EU and Nato of its findings.
“[The federal government] will discuss an appropriate joint response with the partners in the light of the Russian response,” it said.
Mr Navalny’s wife Yulia Navalnaya and Russia’s ambassador to Germany would also be informed of the findings, the statement said.
What happened to Navalny?
Mr Navalny fell ill on a flight from Tomsk to Moscow. His supporters suspect poison was placed in a cup of tea at Tomsk airport.
The flight of the arch-Putin critic was diverted to Omsk, where doctors treated him for three days before he was transferred to the Charité hospital in Berlin.
Doctors at Charité have said his condition is serious but not life-threatening.
Mr Navalny is an anti-corruption campaigner who has led nationwide protests against the authorities and calls Mr Putin’s party a place of “crooks and thieves” that is “sucking the blood out of Russia”.
However, he has been banned from standing against Mr Putin in elections because of a conviction for embezzlement. He denies the allegations, saying his legal troubles are Kremlin reprisals for his fierce criticism.