Navalny, President Vladimir Putin's most prominent domestic critic, died on February 16, 2024, in the "Polar Wolf" penal colony north of the Arctic Circle about 1900 km northeast of Moscow. He was 47.
His death, which the Russian state said was from natural causes, occurred a month before Putin was re-elected for a fifth term in a landslide vote which western nations said was neither free nor fair due to censorship and a crackdown on opponents.
Britain, France, Germany, Sweden and the Netherlands said on Saturday that analyses of samples from Navalny's body had "conclusively" confirmed the presence of epibatidine, a toxin found in poison dart frogs in South America and not found naturally in Russia.
"Navalny died while held in prison, meaning Russia had the means, motive and opportunity to administer this poison to him," they said.
Kremlin spokesman Dmitry Peskov rejected the allegations.
"Naturally, we do not accept such accusations. We disagree with them. We consider them biased and not based on anything. And we strongly reject them," Peskov told reporters.
Maria Zakharova, a spokeswoman for the Russian Foreign Ministry, previously said Moscow would provide relevant comment if and when the countries making the allegations released and detailed their test results.
Until then, the state TASS news agency cited her as saying, the allegations were "merely propaganda aimed at diverting attention from pressing Western issues".
The British government on Saturday declined to respond to a Reuters query about how the samples from Navalny's body were obtained or where they were assessed.
The European joint statement referenced the 2018 Novichok poisoning in Salisbury, England, of former Russian agent Sergei Skripal and his daughter, suggesting that Moscow has form when it comes to using deadly poisons against its enemies.
Russia denies involvement in the Salisbury incident.
It also rejects British allegations that Moscow killed dissident Alexander Litvinenko in London in 2006 by lacing his tea with radioactive polonium-210.
A group of 15 mostly European countries - but also including Australia, New Zealand and Canada - issued a fresh statement on Monday, reiterating their demands for Russia to conduct a transparent investigation into Navalny's death.
The statement, published on the German foreign ministry's website, said that Russian human rights defenders were continuing Navalny's legacy and called on Moscow to release "all political prisoners".
The dart frog toxin allegations were made at the Munich Security Conference ahead of the second anniversary of Navalny's death on Monday.
Yulia Navalnaya, his widow, who had alleged from the outset that her husband had been murdered by the Russian state, said on Monday that the findings provided the necessary proof to back her stance.
"Two years. We have attained the truth, and we will also attain justice one day," Navalnaya wrote on social media above a photograph of her late husband smiling.
