Navalny
© Dimitar Dilkoff/AFP via Getty ImagesAlexei Navalny
Russian opposition leader Alexei Navalny may have been poisoned by a tiny amount of toxin sprinkled in his underwear or socks, according to a retired scientist.

Vladimir Uglev, who claims to have developed the nerve agent Novichok, floated the alternative theory in an interview with Echo of Moscow radio and reported by the Daily Mail on Wednesday.

"They put this substance on his underwear, his underpants, socks, or his undershirt, and that was it," Uglev said.

Supporters of Navalny, 44, believe he sipped spiked tea at an airport before falling ill on a flight from Siberia to Moscow, blaming the Kremlin for the attack.

But Uglev suggested he may have been poisoned before he got to the airport.

"In the morning Alexei woke up, showered, got dressed and went to the airport," he said. "And since the substance acts slower via the skin than say through the digestive system, time passed [before it had an impact]."

Uglev said just a tiny amount of toxin would have been enough to sicken the dissident, one of President Vladimir Putin's fiercest critics.

"Speaking about the quantity of the poison that was needed, it's 1 to 2 milligrams, or approximately a 1/30 of a water drop," the nerve agent expert said. "This is enough to poison a healthy man to death."

But Uglev said it wouldn't be possible that Navalny was poisoned with Novichok specifically — the substance used to poison turncoat Russian spy Sergei Skripal and his daughter in 2018 — because more people would've been sickened.

The scientist has claimed to have synthesized the deadly liquid in 1975.

Doctors at the Charité hospital in Germany said Navalny was poisoned on Aug. 20 but they have not been able to determine the specific substance.

Navalny, who is in a medically induced coma, was transferred to Germany after first being taken to a hospital in Omsk in Siberia.

Uglev said any evidence of the alleged poison used on him may be long gone.

"If it was applied on his underwear and therefore the substance was going through his skin ... he was definitely washed, and the clothes he was wearing, we will never see them again," he said. "No one will ever say where these clothes are, most likely they were burned long ago."

Russia, which has denied involvement in Navalny's and the Skripals' poisonings, has launched a preliminary investigation into Navalny's case.