Yulia Navalnaya, the widow of Russian opposition leader Alexei Navalny, said on Tuesday that foreign laboratory tests have confirmed her husband was poisoned, challenging official Russian claims that his death was the result of natural causes.

Navalny, 47, died suddenly on February 16, 2024, while imprisoned in Russia’s Arctic Circle, a loss that deprived the opposition of its most prominent figure. His death has fueled accusations from his supporters that the Kremlin was responsible — allegations Moscow has dismissed as “nonsense.”

FILE PHOTO: Yulia Navalnaya, Human Rights Activist and wife of late Russian opposition leader Alexei Navalny, attends a press event for the launching of a new television channel to honor the memory of Alexei Navalny and promote free speech in Russia, at the Reporters without Borders (RSF) offices in Paris, France, June 3, 2025. REUTERS/Abdul Saboor/File Photo

In a video posted on X, Navalnaya said that biological samples taken from Navalny were smuggled abroad last year and analyzed by two separate laboratories.

“These labs in two different countries reached the same conclusion: Alexei was killed. More specifically, he was poisoned,” she said, urging the laboratories to release their findings publicly and calling the results an “inconvenient truth.”

navalny death

The latest issue of the Russian weekly newspaper Sobesednik with Russian opposition leader Alexei Navalny’s photo on the front page is pictured in the office of the newspaper in Moscow, Russia, February 26, 2024. REUTERS/Maxim Shemetov

She did not specify what type of poison the labs had identified.

Russian investigators had previously stated that Navalny died of “a combination of diseases,” an explanation his widow has rejected as false.

navalny death

Russian opposition leader Alexei Navalny and his widow Yulia Navalnaya’s mothers, Lyudmila and Alla, stand in front the grave of Alexei Navalny the day after the funeral at the Borisovskoye cemetery in Moscow, Russia, March 2, 2024. REUTERS/Stringer TPX IMAGES OF THE DAY

The U.S. intelligence community has also assessed that Russian President Vladimir Putin did not personally order Navalny’s killing, according to reports by the Associated Press and the Wall Street Journal.