Five European governments say laboratory analysis confirms the use of a South American poison dart frog compound in the Arctic prison death of the Russian opposition leader, deepening an already volatile standoff with Moscow.

In a coordinated declaration released this week, five European governments accused Russia of killing opposition leader Alexei Navalny with a rare toxin derived from South American poison dart frogs, escalating tensions between Moscow and Western capitals.

The United Kingdom, France, Germany, Sweden and the Netherlands said independent forensic laboratories identified epibatidine, a powerful alkaloid compound, in biological samples linked to Navalny’s death while he was detained in an Arctic penal colony two years ago.

Officials described the findings as conclusive, citing advanced toxicological reanalysis using high resolution mass spectrometry and molecular comparison techniques that produced consistent results across multiple accredited laboratories.

Epibatidine is an extremely potent neurotoxin originally isolated from frogs native to parts of Ecuador and neighboring regions, acting on nicotinic acetylcholine receptors and capable of causing respiratory failure in minute quantities.

European authorities emphasized that the compound has no known industrial or medical application in Russia and does not occur naturally there, raising urgent questions about how such a substance could have been obtained and administered inside a high security prison facility.

Navalny, a prominent critic of President Vladimir Putin, had previously survived a poisoning that Western governments attributed to a nerve agent before returning to Russia, where he was arrested and later transferred to a remote Arctic prison complex.

His sudden death in custody prompted international condemnation, with Russian authorities attributing the incident to natural causes while limiting independent access to medical records and forensic material.

Diplomats from the five European countries said the new findings were shared with allied governments and relevant international bodies and are now being examined for potential violations of conventions governing chemical weapons and toxic agents.

Legal specialists note that while epibatidine is naturally derived rather than synthetically engineered, its alleged deliberate use for assassination could still fall within international prohibitions on toxic substances employed for hostile purposes.

Moscow has rejected the accusations and demanded detailed evidence supporting the claims, describing the coordinated announcement as politically motivated and aimed at damaging Russia’s international standing.

In a statement issued through its foreign ministry, Russia said it had not received credible documentation and dismissed the conclusions as speculative and unfounded.

Independent toxicologists observe that epibatidine can be difficult to detect without targeted screening and may degrade rapidly, a factor European officials suggest explains why earlier examinations did not identify the compound.

Security analysts argue that if confirmed, the use of such a rare biological toxin would indicate both technical sophistication and a willingness to explore unconventional methods in suppressing political opposition.

Human rights advocates say the allegations reinforce longstanding concerns about the safety of detainees in Russia and the broader climate confronting critics of the Kremlin.

European governments are now weighing diplomatic and legal responses, including additional sanctions and coordinated action in international forums, while emphasizing transparency and the need for independent scrutiny of the forensic evidence.

As the dispute intensifies, the case threatens to deepen the rift between Russia and Europe and adds a new and unsettling chapter to a history of alleged poisonings that continues to shape the continent’s political and security landscape.