The High Representative of the Union for Foreign Affairs and Security Policy, Josep Borrell, strongly condemned the poisoning of Russian political opponent Alexei Navalny, on the evening of Wednesday 2 September.
Earlier in the day, the German government announced that the Bundeswehr Institute had found traces of a chemical nerve agent from the 'Novichok' group in Mr Navalny's home. The latter had been taken ill on a plane between Siberia and Moscow after drinking tea.
"Toxicological analysis carried out by a German armed forces specialised laboratory proves that Mr Navalny was poisoned by a weapons-grade chemical nerve agent from the 'Novichok' group, developed by the Soviet Union and later by Russia", the High Representative said in a statement.
"The use of chemical weapons under any circumstances is totally unacceptable and a violation of international law", he warned, adding that the EU was closely monitoring the situation and would examine all the implications.
Mr Borrell also considered it essential for the Russian Government to conduct a thorough and transparent investigation into this "assassination attempt". "The case of Alexei Navalny must not go unanswered. Those responsible must be brought to justice", he added.
On Thursday 3 September, the spokesman for the European External Action Service, Peter Stano, calling for this investigation into the poisoning of a Russian citizen to be opened, presumably on Russian territory, said the EU would take action based on the measures taken by Russia.
For her part, German Chancellor Angela Merkel warned that her country would discuss "an appropriate joint response in the light of Russia's statements" with its EU and NATO partners. A discussion confirmed by NATO Secretary General Jens Stoltenberg, who noted that the agent used was "military grade".
The French Foreign Minister explained that Paris would coordinate with Berlin on the response to be given in the "relevant fora", "particularly within the framework of the Organisation for the Prohibition of Chemical Weapons".
The Parliamentary Assembly of the Council of Europe has also reacted to the announcement by the German government. The two co-rapporteurs of this Parliamentary Assembly for the monitoring of the Russian Federation on 2 September expressed their "deepest concern" about "a very alarming situation, which requires an immediate explanation from the Russian authorities".
Ria Oomen-Ruijten (Netherlands, EPP/CD) and Axel Schäfer (Germany, SOC) urged the same authorities to "accept international investigators if such a proposal comes from the international community".
On Thursday 3 September, the Kremlin spokesman said there was "no reason to accuse the Russian state", calling on the West to avoid hasty judgments and saying that Moscow was ready for dialogue. (Original version in French by Camille-Cerise Gessant and Véronique Leblanc)