The plane carrying Navalny, still in an artificially induced coma and gravely ill, landed in the German capital's Tegel airport early Saturday morning and he was taken to The Charité hospital in a large convoy of ambulances and security vehicles. Video showed Navalny lying in a plastic capsule being wheeled on a stretcher by medics into the hospital.
The air ambulance was organised by the Berlin-based nonprofit Cinema for Peace, at the request of Petr Verzilov, a member of Pussy Riot who was evacuated in a similar manner to Germany in 2018 after he was mysteriously poisoned.
Cinema for Peace in a statement said Navalny's condition had remained "stable" following the flight.
Navalny fell suddenly critically ill on Thursday while flying to Moscow from Siberia where he had been meeting with members of a branch of his grassroots activist group. The plane made an emergency landing in the Siberian city of Omsk and he was rushed to a hospital there where he was put in an induced coma and hooked up to a ventilator in intensive care. His colleagues have said they believe he was poisoned, possibly from something slipped into his tea at the airport.
Throughout Thursday and Friday, Navalny's wife and colleagues demanded that he be allowed to be flown to Europe for treatment. But Russian doctors at the hospital for a day refused to allow Navalny to be evacuated, saying his condition did not allow it, even after the German plane arrived in Omsk.
Navalny's colleagues accused the Kremlin of deliberately delaying the flight in order to allow any substance that had poisoned Navalny to pass out of his system and make it harder for Western clinics to detect. Navalny's team in Omsk said large numbers of plain clothes Russian security agents and police were present at the hospital and accused them of managing the doctors' statements, while Russian state media and anonymous law enforcement sources published a series of contradictory theories about what might have caused the opposition leader's sudden sickness.
On Thursday, Germany's Chancellor Angela Merkel as well as France's president Emmanuel Macron had said their countries were ready to treat Navalny.
A German medical team that arrived on the plane were allowed to assess Navalny on Thursday afternoon and gave their unequivocal consent that he was stable enough to fly. Navalny's wife, Yulia, also wrote a letter to president Vladimir Putin asking him to allow Navalny to be evacuated.
Russian doctors finally gave their consent for Navalny to fly on Friday night, though they said they still did not recommend it.
The plane was delayed for several more hours to comply with German flight regulations, but early on Saturday morning Navalny was driven to the airport in Omsk by ambulance and loaded onto Challenger 604 air ambulance which took off and landed a few hours later in Germany.
"The battle for the life and health of Alexey is only beginning and there is a lot more to go through before us, but now at least the first step has been done," Kira Yarmysh, Navalny's spokeswoman wrote on Twitter after the Russian doctors released him to fly.
Another anti-Kremlin activist who works with Navalny, Ilya Yashin, wrote on Twitter he felt "relief as if after long negotiations with terrorists they had freed a hostage."
Navalny, 44, has become Russia's most prominent opposition leader and is known as the most troublesome domestic critic of president Vladimir Putin, having built a grassroots movement largely through blockbuster investigations that have exposed alleged corruption among some of Russia's top officials and some of the country's most powerful business figures, including among Putin's inner circle.
In recent years he has helped coordinate some of the largest protests against the Kremlin in Moscow and recently has been trying to mount a national campaign to undermine Putin's ruling party, United Russia.
A number of Kremlin opponents have been poisoned over the years, including the former Russian intelligence officer Sergey Skripal in the British town of Salisbury in 2018. A pro-democracy activist, Vladimir Kara-Murza was poisoned twice in 2015 and 2017, nearly dying on both occasions and requiring months of rehabilitation. Verzilov, from Pussy Riot, was evacuated to Germany after also being nearly fatally poisoned in the autumn of 2018.
Navalny has been arrested many times and suffered attacks from pro-Kremlin activists. Last year, he was hospitalised with what his colleagues said was poisoning after suffering severe inflammation of his face while serving a brief jail sentence for protesting. Many analysts in Russia have noted that Navalny has made many enemies through his investigations, meaning he might have been targeted by the Kremlin or by others in Russia acting on their own initiative.
"In Navalny’s case, there is no lack of potential enemies," Mark Galeotti a senior associate fellow at the Royal United Services Institute and an expert on Russia's security services wrote in an op-ed for The Moscow Times. Could it be "someone he was investigating for one of his forensically presented and devastating video exposes of official corruption, who assumed that the Kremlin would ultimately forgive direct action? A political figure who feared Navalny’s electoral tactics or who assumed that the Kremlin would like to see him taken out of the equation?" or another power player unconcerned with Putin's reaction, Galeotti speculated. "It's certainly not impossible that the Kremlin was to blame. So far, at least, we don’t know."
Doctors at the Omsk hospital have said they do not believe Navalny was poisoned and have said tests have shown no trace of any poison in his urine or blood. After he was airlifted to Germany, Omsk's regional health ministry published a statement that no oxybates, barbiturates, strychnine, or synthetic poisons had been found. Instead it noted that "alcohol and coffee" had been found in his urine.
The Russian doctors on Thursday said their working diagnosis was that Navalny had suffered a "metabolic disorder", causing his blood sugar to fall sharply that made him lose consciousness on the plane.
Navalny's team have accused the doctors of acting under pressure from the Russian authorities and have said what they have presented as a diagnosis is in fact just a list of symptoms, without explaining the cause. Navalny's personal physician has said he does not have underlying health issues that could have caused such a deterioration.
Navalny's family have said a police officer on Thursday had told them investigators had identified a potentially lethal substance that could have poisoned Navalny and that it posed a danger not just to him but to those around him, meaning those handling him needed to wear protective suits.
The Berlin hospital now treating Navalny, The Charité, said on Saturday it was now conducting a medical examination of Navalny.
"The examination will take some time. And so we ask your patience, We will inform your as soon as we have information," the hospital said in a statement