Five European nations on Saturday blamed Russia for killing late Kremlin critic Alexei Navalny using toxin from poison dart frogs while he was held in an Arctic penal colony two years ago, a claim Moscow rejected as propaganda.

In a joint statement, Britain, France, Germany, Sweden and the Netherlands said analysis of samples from Navalny's body "conclusively" confirmed the presence of epibatidine, a toxin found in poison dart frogs in South America and not found naturally in Russia.

The statement, almost exactly two years after Navalny's death, said Moscow had the means, motive and opportunity to administer the poison.

"Russia claimed that Navalny died of natural causes. But given the toxicity of epibatidine and reported symptoms, poisoning was highly likely the cause of his death," the joint statement said.

The Russian government, which has repeatedly denied any responsibility for Navalny's death, dismissed the latest allegations as "a Western propaganda hoax," according to the Russian state's TASS news agency.

"When the test results are available and the formulas for the substances are disclosed, we will comment accordingly," Russian Foreign Ministry spokesperson Maria Zakharova was quoted as saying by TASS.

"Until then, all such assertions are merely propaganda aimed at diverting attention from pressing Western issues," the news agency cited her as saying.

Zakharova described Navalny as a blogger who was "officially designated as a terrorist and extremist in Russia".

The British government declined to comment on questions about how the samples from Navalny's body were obtained or where they were assessed.

British Foreign Minister Yvette Cooper told reporters that "UK scientists worked with our European partners to pursue the truth" on Navalny's death.

Navalny died in an Arctic prison colony in February 2024, after being convicted of extremism and other charges, all of which he denied. (Reuters)