Alexei Navalny has arrived in Germany's capital Berlin, where a non government organisation says he is in a 'stable' condition.
An air ambulance landed in the German capital on Saturday carrying Russian opposition leader Alexei Navalny, who has suffered a suspected poisoning, after a day-long standoff over his medical evacuation.
The plane, chartered by the German NGO Cinema for Peace, landed at 8:47 am local time at Tegel airport in Berlin, where Navalny is expected to be transferred to the Charite hospital for treatment.
"Navalny's condition is stable," Jaka Bizilj, the head of the Cinema for Peace, the NGO chartered the flight, said after the flight touched down.
The 44-year-old lawyer and anti-corruption campaigner, one of President Vladimir Putin's fiercest critics, fell into a coma after becoming suddenly ill Thursday on a plane to Moscow that had to make an emergency landing in Omsk.
His aides say they believe he was poisoned, apparently by a cup of tea at the airport, and blamed Putin, though Russian doctors said tests showed no trace of any poison.
Doctors treating him in Omsk had refused to let Mr Navalny leave but reversed course after his family and staff demanded he be allowed to travel to Germany.
The plane, chartered by the German NGO Cinema for Peace, took off around 0200 GMT to fly Mr Navalny to Berlin's Charite hospital for treatment.
Mr Navalny's wife Yulia posted a picture on Instagram of him being lifted into the plane on a covered stretcher and thanked supporters for their "persistence".
"Without your support, we wouldn't have been able to take him!" she wrote.
The ambulance arrived at the Omsk Emergency Hospital No. 1 early Saturday and masked medics put Mr Navalny inside on a stretcher.
Russian doctors have said he is in a coma and breathing through a ventilator in a grave state.
They have said tests did not find any trace of poison, however, and said Mr Navalny appeared to have a "metabolic disorder" and to have suffered a sharp drop in blood sugar levels.
The regional interior ministry said police detected an industrial chemical after swabbing Mr Navalny and his luggage, although doctors said this would not have caused his condition.
The air ambulance arrived in Omsk on Friday morning but Russian doctors initially said that Mr Navalny was too "unstable" to be moved.
Appeal to Putin
They announced on Friday evening that they had agreed to let him be transferred after German doctors examined him and the Cinema for Peace foundation said they were "willing and able" to transport him to Berlin.
The turnaround also followed a letter from Mr Navalny's wife with a direct appeal to President Putin and after aides asked the European Court of Human Rights to intervene with the Russian government.
Mr Navalny is the latest in a long line of Kremlin critics who have fallen seriously ill or died in apparent poisonings.
His wife told journalists that she wanted Mr Navalny to be "in an independent hospital, whose doctors we trust".
His spokeswoman Kira Yarmysh tweeted that "the battle for Alexei's life and health is just beginning... but at least now we've taken the first step."
The air ambulance was dispatched to take Mr Navalny to Berlin after Chancellor Angela Merkel extended an offer of treatment.
European Union leaders including Ms Merkel and French President Emmanuel Macron have voiced concern for Mr Navalny, who has faced repeated physical attacks and prosecutions in more than a decade of opposition to Russian authorities.
Mr Navalny lost consciousness shortly after his plane took off on Thursday from Tomsk in Siberia, where he was working to support opposition candidates ahead of regional elections next month.
Ms Yarmysh said he had seemed "absolutely fine" before boarding the flight and had only consumed a cup of tea at the airport.
She said she was sure he had suffered from an "intentional poisoning" and blamed Mr Putin.
She also claimed Russia's refusal to evacuate Mr Navalny was a ploy to "play for time" and make it impossible to trace poison, posing a "critical threat to his life".
Mr Navalny has made many enemies with his anti-corruption investigations, which often reveal the lavish lifestyles of Russia's elite and attract millions of views online.
He is the latest in a long line of Kremlin critics who have fallen seriously ill or died in apparent poisonings.
The director of the Anti-Corruption Foundation that Mr Navalny founded, Ivan Zhdanov, confirmed on social media that the organisation was "continuing its work".
Many supporters expressed relief that he was going for treatment outside Russia.
"I feel as relieved now as if terrorists had freed a hostage after long negotiations," fellow opposition politician Ilya Yashin tweeted, criticising the delay in Mr Navalny's departure.
"I want to believe that this wasted time won't cost Alexei his life."