Russian Opposition politician Alexei Navalny, who is in a coma after being allegedly poisoned, was brought to Germany’s capital Berlin for medical treatment on Saturday, AP reported, citing his spokesperson.

The plane carrying Navalny took off from the Siberian city of Omsk early on Saturday. Navalany’s wife, Yulia, was also on board, according to Al Jazeera.

On Friday, physicians overseeing Navalny’s health said his condition was too unstable for him to be moved after the German specialists arrived on a plane equipped with advanced equipment.

Navalny’s supporters have alleged that the statement of the physicians was a ploy of the Russian government to delay the politician’s transfer so that the poison would not be traceable. Later, Deputy chief doctor of the Omsk hospital Anatoly Kalinichenko said his condition had stabilised and he could be moved if his family wished.

Dr Yaroslav Ashikhmin, Navalny’s physician in Moscow, told the news agency that the politician was safer in the flight to Germany than staying at the Omsk hospital.

On Thursday, France and Germany said they were ready to offer Navalny and his family assistance and insisted on a an investigation into what happened. The next day, the European Union said it had urged the Kremlin to permit Navalny to be taken abroad for treatment.

Forty-four-year-old Navalny, an opponent of Russian President Vladimir Putin, felt unwell on a flight back to Moscow from Tomsk, a city in Siberia, his spokesperson Kira Yarmysh said in a tweet. Yarmysh tweeted that Navalny has toxic poisoning. The plane made an emergency landing in Omsk city in Southwestern Siberia on Thursday.

Later, she tweeted that “state propaganda” would have people believe that there was no deliberate poisoning, but the fact is that this was no ordinary poison.

Navalny had campaigned to run against Putin in the 2018 presidential elections, but was barred from contesting. He set up a network of campaign offices across Russia and has been putting forth candidates to contest regional elections against Putin’s party, United Russia.

Navalny’s Foundation for Fighting Corruption has been exposing graft among high-level government officials. Navalny has labelled United Russia as the “party of crooks and thieves”. However, last month, Navalny had to shut down the organisation after Yevgeny Prigozin, a businessman with close ties to the Kremlin, filed a lawsuit against him.