Five European countries have jointly accused the Russian state of poisoning Kremlin critic Alexei Navalny with a rare toxin derived from South American poison dart frogs, after new forensic analyses linked the substance to his death in 2024.

A statement by the governments of the United Kingdom, France, Germany, Sweden and the Netherlands said laboratory examination of samples taken from Navalny’s body “conclusively confirmed the presence of epibatidine” — a powerful neurotoxin found in dart frogs but not naturally occurring in Russia. They said the discovery strongly suggests the poison was administered while Navalny was held in a Siberian penal colony two years ago.

Officials at the Munich Security Conference where the findings were released said that only the Russian state had the means, motive and opportunity to carry out the attack, and that the case has been referred to the Organisation for the Prohibition of Chemical Weapons for review under international law.

Navalny — the most prominent critic of President Vladimir Putin — died in February 2024 while serving a long sentence in an Arctic prison. Russian authorities have repeatedly rejected the allegations, dismissing the European claims as politically motivated and saying there has been no official disclosure of the toxological test results.

His widow, Yulia Navalnaya, has long maintained he was murdered and welcomed the latest findings as “scientifically proven facts,” underscoring long-standing Western accusations of Moscow’s use of poison against dissenters.