Britain, France, Germany, Estonia and Belgium said in a joint letter sent to the UN Security Council that poisoning Russian dissident Alexei Navalny "poses a threat to international peace and security," while Russia accused him of being an agent of the US intelligence agency "CIA".
The five countries demanded Russia to disclose, in an urgent, full and transparent manner, the circumstances of the attack and to inform the Security Council of the matter.
The United States did not sign the letter, but Secretary of State Mike Pompeo said the Russian government should provide a full explanation for the poisoning of Alexei Navalny and hold those involved responsible.
Russia denied any involvement in the incident, and said that it had not yet found evidence of a crime, and the Russian mission to the United Nations had not yet commented on the letter.
The Kremlin rejected the accusations of opposition Navalny, in which he held President Vladimir Putin responsible for his poisoning, and Russian presidential spokesperson Dmitry Peskov said in two statements reported by the official news agency "TASS" that such accusations against the Russian president are totally baseless and unacceptable.
The spokesman accused Navalny of working with the CIA, saying, "This is not the first time that they have given him instructions."
Navalny was airlifted to Berlin in August after ill health on a Russian domestic flight, and he received treatment for what Germany said was poisoning with the nerve-killer Novichok gas, before he was discharged from hospital in September.