The German government said Monday that laboratories in France and Sweden have confirmed its own findings that Russian opposition leader Alexei Navalny was poisoned with a Novichok nerve agent.

Chancellor Angela Merkel’s spokesman Steffen Seibert said in a statement that Germany had asked France and Sweden “for an independent review of the German evidence (of Novichok poisoning) on the basis of new samples from Mr Navalny,” who is receiving treatment in Berlin.

Also see: The curious case of Russian Kremlin critics who were allegedly poisoned

“The results of this review at specialised laboratories in France and Sweden are now available and confirm the German evidence (of Novichok poisoning),” Seibert said.

“We renew the call for Russia to explain itself on the events. We are in close contact with our European partners on further steps,” he added.

Also read: Germany approves Russian request to assist in Navalny probe

Earlier, Berlin prosecutors had said it would investigate the Navalny case for suspected poisoning, and hand information to Moscow, if he agreed.

Moscow has insisted it has seen no evidence he was poisoned and earlier on Friday said it would ask to send investigators to Berlin in response to the German demands.

The prosecutor’s office in the German capital said it had been commissioned by the regional justice department “to provide legal assistance over the Russian request for legal assistance and to obtain information on the state of health of A. Navalny – subject to his consent”.

Navalny, President Vladimir Putin’s highest-profile critic, was flown to Germany last month after falling violently ill while travelling in Siberia. He is very unlikely to agree to Germany sharing information with the Russian government, which his supporters have accused of attempted murder.

Some senior German politicians have said Berlin should revoke support for Nord Stream 2, a big gas pipeline from Russia to Germany set to open next year. Such a move would amount to the most drastic economic penalty the West has imposed on Russia since the Soviet era.

The transport department of Russia’s interior ministry in Siberia said it wanted to send investigators to work alongside German colleagues on the case, after reports that Navalny had emerged from a coma.

“This request will include an application for the possible presence of Russian internal affairs investigators … and a Russian specialist when German colleagues are conducting investigations with Navalny, doctors and experts,” the ministry said in a statement.

Russia has not opened a criminal investigation and is sticking to its position that it would first need hard evidence from Germany that Navalny was poisoned. Foreign Minister Sergei Lavrov said on Friday that German accusations over the case were “groundless”.