Russia on Sunday accused Germany of stalling efforts to probe opposition politician Alexei Navalny's case after Berlin demanded Moscow provide an explanation over his poisoning or face sanctions.
Russian foreign ministry spokeswoman Maria Zakharova accused German authorities of failing to respond to a request by Russian prosecutors sent on August 27.
She spoke after German Foreign Minister Heiko Maas said Russia must soon provide an explanation over Navalny's poisoning with Novichok, a banned nerve agent developed in the Soviet Union.
"Dear Mr Maas, if the German government is sincere in its statements then it should be interested in preparing a response to a request of the Russian Prosecutor General's Office as soon as possible," Zakharova said.
"So far we are not certain that Germany is not playing a double game," she added. "Where is the 'urgency' you are insisting upon?
"By not sending its answer, Berlin is stalling the process of investigation for which it's calling. On purpose?"
Germany, the current head of the European Union, will discuss possible sanctions on Russia over the poisoning of Russian President Vladimir Putin's top foe if the Kremlin does not provide an explanation soon, Maas said Sunday.
Navalny fell ill on a flight last month and was treated in a Siberian hospital before being evacuated to Berlin.
Germany said last week there was "unequivocal evidence" that the Russian opposition leader had been poisoned using Novichok.
"If in the coming days Russia does not help clarify what happened, we will be compelled to discuss a response with our allies," Maas told German daily Bild.
Any sanctions decided should be "targeted", he added.
Western leaders and many Russians have expressed horror at what Navalny's allies say is the first known use of chemical weapons against a high-profile opposition leader on Russian soil.
Earlier this week Foreign Minister Sergei Lavrov said Russia had "nothing to hide" and the Kremlin said Russian doctors had found no proof Navalny was poisoned.