Britain blames Russia for 'barbaric' death of Vladimir Putin critic Alexei Navalny using dart frog toxin

However, it remains unclear how the unique neurotoxin - which is classed as a chemical weapon - could have been administered by Putin's team.

This morning, two days before the two-year anniversary of his death, the Foreign Secretary, Yvette Cooper, said: "Since Yulia Navalnaya announced the loss of her husband here in Munich two years ago, the UK has pursued the truth of Alexei Navalny’s death with fierce determination.

"Only the Russian Government had the means, motive and opportunity to deploy this lethal toxin against Alexei Navalny during his imprisonment in Russia.

"Today, beside his widow, the UK is shining a light on the Kremlin’s barbaric plot to silence his voice.

"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 Foreign Office added: “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."

The Foreign Office condemned Moscow for having "brazenly developed and deployed this poison in violation of the Chemical Weapons Convention".

It added: "Russia's egregious and irresponsible actions, including its barbaric full-scale invasion of Ukraine continue to threaten our shared security.

"Time and again the Russian state shows the depths it is willing to go to terrorise people and undermine democracy."

Quoting the Russian dissident, Ms Cooper said: "He said: 'We must do what they fear, tell the truth, spread the truth that is the most powerful weapon'."

Ms Cooper's revelation came just hours after her boss Sir Keir Starmer told European leaders he wanted to bolster their military and defence alliance with Russia proving "its appetite for aggression".

At the press conference at the Munich Security Conference, his widow was joined by foreign ministers from the UK, Germany, Sweden and the Netherlands.

All four nations, in addition to France, have been jointly working together to establish her husband's cause of death.

The findings will now be submitted to the UN's chemical weapons watchdog, the Organisation for the Prohibition of Chemical Weapons.

"It is hard for me to find the right words," Mrs Navalnya said today, overcome with emotion, reflecting on her attendance of the global summit two years ago.

"It was the most horrible day in my life. I came to the stage and I said my husband, Alexei Navalny, was poisoned. What could else happen with Putin's number one enemy in a Russian prison?

"But now I understand and I know it is not just words. It is scientific proof."

In the past, Russian officials has said opponent's death was not suspicious and came about due to "combined diseases".

Since his death, his supporters led by his widow Mrs Navalny has persistently pursued the cause of his death, insisting the Kremlin had killed him.

In 2024, she claimed analysis of biological materials from his cell revealed that her husband had been killed, calling on the laboratories to publish the reports.

However, they refused due to "political considerations".

In the lead up to his death, it is believed Mr Navalny had been out for a walk when he began to feel ill, and was escorted back to his jail cell, where he was left "moaning in pain" before vomiting.

Mrs Navalny claimed prison guards looked on at the man flailing in agony for 40 minutes before calling emergency services.

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