Kremlin critic Alexey Navalny unconscious in intensive care after being hospitalised in Siberian city of Omsk, media reports and his spokesperson says.

Alexei Navalny is known for his anti-corruption campaigns against top officials and outspoken criticism of President Vladimir Putin.
Alexei Navalny is known for his anti-corruption campaigns against top officials and outspoken criticism of President Vladimir Putin. (Reuters)

Russian opposition leader Alexey Navalny is unconscious and in intensive care in hospital after apparently being poisoned, his spokeswoman has said.

Kira Yarmysh said Navalny was flying from Siberia to Moscow and his plane made an emergency landing after he fell ill.

"Alexei has toxic poisoning," she wrote on Twitter. "Alexei is now in intensive care."

Yarmysh said "We think that Alexey was poisoned with something mixed in his tea. That was the only thing he drank in the morning."

"Doctors say the poison was quickly absorbed through the hot liquid," she added.

Anatoliy Kalinichenko, deputy chief doctor of the Omsk hospital where the politician is being treated, told reporters that Navalny was in grave, yet stable condition. 

Kalinichenko said doctors are considering a variety of diagnoses, including poisoning, but refused to give details, citing a law preventing doctors from disclosing confidential patient information.

READ MORE: Who is Alexei Navalny — Russian dissenter and Putin's foe?

Past attacks

Navalny is in the intensive care unit for toxicology patients in Omsk Emergency Hospital No. 1, the TASS state news agency confirmed.

The 44-year-old, known for his anti-corruption campaigns against top officials and outspoken criticism of President Vladimir Putin, has suffered physical attacks in the past.

He suffered chemical burns to his eye in 2017 when attackers threw green dye used as a disinfectant at his face outside his office.

Last year, Navalny was rushed to a hospital from prison where he was serving a sentence following an administrative arrest, with what his team said was suspected poisoning. 

Doctors then said he had a severe allergic attack and discharged him back to prison the following day. 

Criminal probe sought

In the interview with Echo Moskvy, Yarmysh said she believed the suspected poisoning was connected to this year’s regional election campaign.

Vyacheslav Gimadi, a lawyer with Navalny's foundation, said the team is requesting Russia's Investigative Committee to open a criminal probe.

"There is no doubt that Navalny was poisoned because of his political stance and activity," Gimadi said in a tweet.

Navalny is not the first opposition figure to come down with a mysterious poisoning. 

In 2018, Pyotr Verzilov, a member of Russia's protest group Pussy Riot, ended up in an intensive care unit after a suspected poisoning and had to be flown to Berlin for treatment. 

Opposition activist Vladimir Kara-Murza was hospitalised with poisoning symptoms twice — in 2015 and 2017. Both said they believed they were poisoned for their political activity.

READ MORE: Pussy Riot activist may have 'medicine poisoning'

Source: TRTWorld and agencies