The European Union must give a clear response towards Russia by imposing sanctions following the poisoning of Kremlin critic Alexei Navalny with an internationally banned nerve agent, German Foreign Minister Heiko Maas said Saturday.

"I am convinced that there will be no longer any way around sanctions," Maas told news portal t-online in an interview.

"Sanctions must always be targeted and proportionate. But such a grave violation of the International Chemical Weapons Convention cannot be left unanswered. On this, we're united in Europe," Maas added.

Germany currently holds the rotating presidency of the 27-member bloc.

Navalny, a corruption investigator who is Russian President Vladimir Putin’s fiercest critic, was flown to Germany two days after falling ill on Aug. 20 on a domestic flight in Russia. He spent 32 days in the hospital, 24 of them in intensive care before doctors deemed his condition sufficiently improved for him to be discharged.

German chemical weapons experts determined that he was poisoned with the Soviet-era Novichok, the class of nerve agent that Britain said was used in a 2018 attack on former Russian spy Sergei Skripal and his daughter in Salisbury, England. Labs in France and Sweden corroborated the German findings.

In comments to Germany Der Spiegel magazine earlier this week, Navalny accused Putin of being behind the poisoning.

He asserted that his poisoning with a Novichok nerve agent only could have been ordered by the heads of Russia's military, domestic, or foreign intelligence agencies, officials who "cannot make a decision like that without being instructed by Putin. They report to him."

German Chancellor Angela Merkel called the poisoning an attempted murder and she and other world leaders have demanded that Russia fully investigate the case.