The anti-corruption campaigner, suddenly took ill during a flight and the plane had to make an emergency landing in Omsk, where doctors said he was in a coma and they were trying to save his life.
Also Read: US Prez Trump's Former Adviser Steve Bannon Arrested, Charged With Fraud Over 'We Build The Wall' Campaign
His spokeswoman said “Navalny was unconscious in a hospital after suffering from suspected poisoning, his spokeswoman said on Thursday.”
Who is Kremlin critic Alexei Navalny?
Alexeie Navalny, the man who has served several jail sentences for speaking out vociferously against Russian President Putin, made a name for himself by exposing official corruption, labelling Putin's United Russia as "the party of crooks and thieves”.
He emerged as a critic of corruption, Russian President Vladimir Putin and his government.
He has organized demonstrations advocating reform and against political corruption, Putin and Putin's political allies; he has run for a political office on the same platform.
In 2012, The Wall Street Journal described him as "the man Vladimir Putin fears most".
Who poisoned Navalny? People gather in support of the opposition leader
Several people, holding placards, and slogans in support of Navalny gathered on streets to express support to him.
Police officers detain a participant of a gathering to express support for Alexei Navalny after he was rushed to intensive care in Siberia suffering from what his spokeswoman said was a suspected poisoning, in front of the headquarters of the FSB security services in downtown Moscow on August 20, 2020. (Photo by Alexander NEMENOV / AFP)
Case of toxic poisoning:
Kira Yarmysh, the press secretary for the Anti-Corruption Foundation, which Navalny founded in 2011, tweeted: "This morning Navalny was returning to Moscow from Tomsk. During the flight, he felt ill. The plane made an urgent landing in Omsk. Alexei has toxic poisoning."
"We suspect that Alexei was poisoned by something mixed into (his) tea. It was the only thing he drank since morning.
"Doctors are saying that the toxic agent absorbed faster through the hot liquid. Right now Alexei is unconscious."
Yarmysh later tweeted that Navalny, the 44-year-old staunch critic of President Vladimir Putin, was on a ventilator and in a coma, and that the Omsk Emergency Hospital was now full of police officers, the BBC reported.
She said doctors were initially ready to share any information but were now saying the toxicology tests were delayed and were "clearly playing for time, and not saying what they know".
Navalny is in the intensive care unit.
What the doctors are saying?
The hospital's chief physician Alexander Murakhovsky earlier told TASS News Agency that he was in serious condition, adding that doctors were yet to diagnose his case.
Addressing reporters, Anatoly Kalinichenko, deputy chief physician, said: "There are diagnoses that have been ruled out or are in the process of confirmation. (Doctors) are holding consultations. We will decide on the diagnosis later in the day.
"Symptomatic treatment (is currently being conducted)."
Kalinichenko added it was not yet certain if Navalny was poisoned.
(inputs from agencies)