Five European countries have claimed that the death of Russian opposition leader and Kremlin critic Alexei Navalny was caused by a lethal toxin found in a South American poison dart frog.

In a joint statement issued on Saturday, the governments of the United Kingdom, Sweden, France, Germany and the Netherlands said that laboratory analysis of samples taken from Navalny’s body confirmed the presence of a chemical known as epibatidine. The statement added that the substance does not occur naturally in Russia.

Navalny died two years ago, in 2024, while being held in a penal colony north of the Arctic Circle. The five European nations alleged that only Moscow had the means, motive and opportunity to administer the toxin while he was in custody. They argued that the capabilities required to carry out such an act were available solely to the Russian state.

Russian authorities have repeatedly denied any responsibility for Navalny’s death. According to the state news agency TASS, Foreign Ministry spokesperson Maria Zakharova dismissed the claims about the use of frog poison as propaganda.

The announcement came during the Munich Security Conference in Germany. Notably, Navalny’s death was also announced while the same conference was taking place in 2024.

Speaking at the gathering on Saturday, Navalny’s wife Yulia Navalnaya recalled the events of two years ago. “Two years ago I was here in Munich. It was the most terrible day of my life. I came to the stage and said that my husband, Alexei Navalny, had been poisoned,” she said.