Berlin prosecutors said on Friday they would investigate the case of Russian opposition politician Alexei Navalny, who is being treated in Berlin for suspected poisoning, and hand information to Moscow - if he agreed.
The German government had earlier said it would not investigate the case because the poisoning took place in Russia.
It has accused Russia of trying to poison Navalny and demanded an explanation from Moscow for what it said was the banned Soviet-era nerve agent Novichok found in his body by German doctors after he was airlifted from Russia for treatment.
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”."