Navalny has been in a coma in intensive care since Thursday.
The 44-year-old staunch critic of President Vladimir Putin fell ill on a flight back to Moscow from the Siberian city of Tomsk, his spokeswoman Kira Yarmysh said on Twitter. Yarmysh said Navalny drank tea that appeared to have been laced with a toxin.

Russian doctors say there is no evidence of poisoning, and the Kremlin denied the authorities tried to prevent the transfer from happening. But Navalny was only allowed to leave Russia after more than 24 hours of wrangling over his condition and treatment.

“Alexey is taken to the medical aircraft. Yulia is with him,” Yarmysh wrote on Twitter. Yulia is Navalny’s wife. She was initially refused access to him.

On Friday, doctors at Omsk Ambulance Hospital No. 1, where the politician was being treated, remained tight-lipped about his diagnosis saying only that they were considering a variety of theories, including poisoning. Local health officials said they found no indication that Navalny had suffered from a heart attack, stroke or the coronavirus.

Navalny will now be treated by doctors in Berlin.

He is the effective face of political opposition to Putin and he has been in and out of jail for his activism against Russia’s longtime leader.

Last year, Navalny claimed he was poisoned while serving a short jail sentence. Doctors said he had a severe allergic reaction to an unknown substance. He was left partially blind in one eye after a pro-Putin activist attacked him with a chemical in 2017.

Navalny attempted to run against Putin in Russia’s 2018 presidential elections but was barred from participating over a fraud conviction he alleged was politically motivated.

Putin critics meet tragedy

Many of Putin’s opponents — journalists, politicians, former associates — have died in suspicious circumstances.

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The British government concluded that Russian military agents were behind the poisoning attack in 2018 in Britain against former Moscow spy Sergei Skripal and his daughter Julia, in which Novichok, a highly toxic, military-grade nerve agent, was used.

British authorities concluded that Alexander Litvinenko, another former Russian spy, was poisoned to death at the Kremlin’s behest in a London hotel in 2006.

Anna Politkovskaya, an investigative journalist who was a critic of the Kremlin and exposed Russian human rights abuses, was murdered in 2006.

Boris Berezovsky, an oligarch who was once Putin’s right-hand man, was found hanged at his mansion outside London in 2013.

Russian opposition activist Vladimir Kara-Murza, a member of the pro-democracy group Open Russia, said attempts were made to poison him in 2015 and 2017.

On both occasions, Kara-Murza nearly died.

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In 2018, Nikolai Glushkov, a close associate of Berezovsky’s whom Moscow accused of embezzling money from Aeroflot, Russia’s state airline, was found strangled in his home near London. Glushkov’s name was on the top of an extradition list of 51 Russian citizens that Moscow described as “fugitives from justice” but “welcome” in Britain. The list was published by the Russian Embassy in London.

That same year, Pyotr Verzilov, a member of the feminist performance art protest group Pussy Riot, was flown to a hospital in Germany after suffering what doctors said was a near-fatal poisoning by an unknown substance.

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Navalny led nationwide protests against Putin, whose administration he described as full of “crooks and thieves” who are “sucking the blood out of Russia.”

The Kremlin denies using violence for political ends.

Kremlin spokesman Dmitry Peskov said Thursday that law enforcement would launch an investigation if the poisoning is confirmed.

This is Putin. Whether he gave the order or not, the fault lies entirely with him,” said Yarmysh, Navalny’s spokeswoman.

“Unfortunately, the nature of these things in Russia is that the poisoning could have just as likely been committed by an agent of the state as by some ill-wisher doing what (this person) thinks the state wants without the government ordering or even knowing of the attack,” said Anna Arutunyan, author of “The Putin Mystique.”

“If the government was not involved, then its inability or lack of will to hold attackers accountable for past poisonings creates a culture where these kinds of things become possible – a culture beyond government control, which is just as bad,” she said.

This year, two Russian doctors died and another was seriously injured in mysterious falls from hospital windows after they reportedly came under pressure over working conditions in the coronavirus pandemic.