Alexei Navalny, Russian President Vladimir Putin’s most popular challenger, is in intensive care in Siberia after an apparent poisoning, according to his spokeswoman.
Mr Navalny fell ill on a flight from Tomsk to Moscow on Thursday morning and lost consciousness on the aircraft after drinking a cup of tea in the airport, Kira Yarmysh said.
The aircraft made an emergency landing in the nearby city of Omsk, where Mr Navalny was taken to hospital and placed on a respirator. Local health officials said Mr Navalny was in intensive care and doctors were “performing all necessary tests”.
Ms Yarmysh said: “We suspect Alexei was poisoned with something mixed into his tea. It was the only thing he drank all morning. Doctors said that the toxin was absorbed more quickly through hot liquid.”
Mr Navalny, 44, is the face of grassroots opposition to the Kremlin and no stranger to threats for his activism. Last year he claimed that he was poisoned while serving one of his many short jail sentences, for protesting against Mr Putin, with an unknown substance that provoked a severe allergic reaction.
In 2017, a pro-Kremlin activist attacked him with a chemical that left him partially blind in one eye.
Other prominent Russian opposition activists have also been hospitalised after apparent poisonings in recent years. The UK accused Russian military intelligence agents of poisoning spy Sergei Skripal and his daughter Yulia with Novichok, a military-grade nerve agent, in the country in 2018.
In 2006, Alexander Litvinenko, a former Russian spy who became a critic of Mr Putin in exile, died in London after drinking tea laced with polonium-210, a radioactive isotope.
More recently, in 2018, Petr Verzilov, publisher of news site Mediazona and an inspiration for dissident artists Pussy Riot, spent a month in intensive care after an unknown toxin cost him his ability to speak and much of his sight.
Journalist Vladimir Kara-Murza believes he was deliberately poisoned twice in three years with an unknown substance that left him near death.
Doctors were unable to determine what was apparently used to poison the men, while police did not establish any potential suspects.
“For the first few days the doctors were fighting for my life and weren’t sure I’d survive,” Mr Verzilov said on Twitter. “They haven’t even tried to investigate the attempt on my life for two years.”