Russian opposition leader Alexei Navalny was fatally poisoned with a toxin from Ecuadorian dart frogs that is 200 times stronger than morphine — a “despicable” killing which could only have been carried out by Russia, five Western nations and the activist’s widow, Yulia Navalnaya, said Saturday.

Navalny, 47, died Feb. 16, 2024 in an Arctic penal colony, sparking outrage around the world.

Foreign ministers from the United Kingdom, Germany, Sweden, and the Netherlands joined Navalnaya as she made the revelation to reporters at the annual Munich Security Conference — the same event where she announced his death two years earlier. 

The neurotoxin, known as epibatidine, is classified as a chemical weapon and is used by South American tribes as they hunt, according to Sky News.

“It is hard for me to find the right words,” the widow said as she announced the findings, which she intends to submit to the United Nation’s chemical weapons watchdog.

Testing had “conclusively confirmed the presence of epibatidine,” the four nations, along with France, said in a statement.

“Russia claimed that Navalny died of natural causes,” the countries said. “But given the toxicity of epibatidine and reported symptoms, poisoning was highly likely the cause of his death. Navalny died while held in prison, meaning Russia had the means, motive and opportunity to administer this poison to him.” 

There had long been suspicion in Western governments of Russia’s claim that Navalny — Vladimir Putin’s most popular critic — had died of natural causes. 

The five nations had banded together to probe the cause of Navalny’s death. 

“Russia saw Navalny as a threat. By using this form of poison the Russian state demonstrated the despicable tools it has at its disposal and the overwhelming fear it has of political opposition,” the Western governments said.

“Russian authorities are going to tell their own story,” then-President Joe Biden said in a furious speech after Navalny’s death. “Make no mistake: [Russian President Vladimir] Putin is responsible for Navalny’s death.”

In 2020, Navalny was poisoned with the nerve agent Novichok, a nerve agent dating to the Soviet era. He ended up receiving medical treatment in Germany, then returned to Russia to continue his role as a leading opposition figure. 

Upon his return, he was a constant thorn in Moscow’s side, posting online exposes about the wealth accumulated by Russian oligarchs around Putin.

British Foreign Secretary Yvette Cooper spoke to the Putin regime’s motive for the poisoning, which took place amid an ongoing clampdown on dissent while Russia waged war on Ukraine.

“Russia saw Navalny as a threat. By using this form of poison the Russian state demonstrated the despicable tools it has at its disposal and the overwhelming fear it has of political opposition,” she said.

Navalny had been serving a 19-year prison sentence that was itself condemned by western watchdogs. 

The US did not join the announcement. 

The office of the Director of National Intelligence did not immediately respond to The Post’s request for comment.

The toxin is derived from the Epipedobates tricolor, known as the Phantasmal Poison Frog and the Phantasmal Poison-arrow Frog.

The tiny animal’s snout is just 23 mm long, according to amphibiaweb.org.

But it is considered one of the earth’s most poisonous animals.

It is usually dark red or brown, and bears three yellow-white stripes. Like many tropical frogs, it is considered vulnerable due to environmental and other factors, and can be found on the slopes of the Andes about 1,000 feet.

Its obscurity is one reason governments concluded only the Russian state would have been capable of carrying out the poison attack. 

“Only the Russian state had the means, motive and opportunity to deploy this lethal toxin to target Navalny during his imprisonment in a Russian penal colony in Siberia, and we hold it responsible for his death,” the five Western nations said.

“Epibatidine can be found naturally in dart frogs in the wild in South America. Dart frogs in captivity do not produce this toxin and it is not found naturally in Russia. There is no innocent explanation for its presence in Navalny’s body.”