Germany asserts that the prominent critic of President Vladimir Putin was poisoned while the Russian Foreign Ministry has accused Berlin of "bluffing." G7 ministers have demanded Moscow "urgently" finds the perpetrators.
On Tuesday, Russia's Foreign Ministry called on Germany's ambassador to Moscow to attend talks regarding accusations that Alexei Navalny had been poisoned.
Officials in Berlin say they have evidence to support their claim. Russian authorities say Germany's government is "bluffing."
The opposition figure Navalny was airlifted to Berlin last month after he fell ill on a domestic flight in Russia. Medics in Berlin say evidence indicates that he was poisoned with the nerve agent Novichok, a statement supported by German Foreign Minister Heiko Maas.
The Group of Seven foreign ministers later on Tuesday condemned the "confirmed poisoning" of Navalny, according to a statement released by the US State Department.
"We, the G7 foreign ministers of Canada, France, Germany, Italy, Japan, the United Kingdom and the United States of America and the High Representative of the European Union, are united in condemning, in the strongest possible terms, the confirmed poisoning of Alexei Navalny," said the statement.
"We call on Russia to urgently and fully establish transparency on who is responsible for this abhorrent poisoning attack and, bearing in mind Russia's commitments under the Chemical Weapons Convention, to bring the perpetrators to justice."
"This is too serious to allow German officials to keep everything to themselves," Russian Foreign Ministry spokeswoman Maria Zakharova wrote on Facebook. "We expect Berlin to provide all available information: the results of laboratory studies and the 'evidence' that the foreign office has. We are awaiting the German ambassador in Smolensk."
"It is obvious Berlin is bluffing, serving a dirty political agenda," she claimed.
On Monday, the UN called for Russia to cooperate in an independent investigation into the poisoning. The Kremlin has denied any involvement.
Roderich Kiesewetter a foreign-policy expert from German Chancellor Angela Merkel's governing CDU party told DW on Tuesday that Germany and Europe would have to make a decision on "how to tackle Russia."
At issue was not the question of whether or not to continue work on the Nord Stream 2 gas pipeline from Russia to Germany, said Kiesewetter, a member of the German parliament's Foreign Affairs Committee.
"The main issue is that a toxin which is forbidden by international law was used inside Russia," he said.
"We need a European answer to show that we are closely aligned with the international rules-based order which was severely violated by this event in Russia."
Navalny is the latest of many high-level Putin critics who have been poisoned.
After being airlifted to Berlin, he remained in a medically-induced coma. He was woken up on Monday.
Germany has not confirmed whether they will publish the full results of the toxicology tests which were carried out on Navalny.