It is "fairly likely" Russian opposition figure Alexei Navalny was poisoned, the German government says, as the Kremlin critic is treated in a Berlin hospital.
The 44-year-old was brought to Berlin on Saturday from Siberia, with what Russian doctors have blamed on a metabolic disorder.
"We are dealing with a patient who it is fairly likely was poisoned," Angela Merkel's spokesman Steffen Seibert told reporters on Monday.
The Kremlin critic, Russia's best-known opposition figure, was rushed into intensive care on Thursday after his plane made an emergency landing in the Siberian city of Omsk.
Russian opposition figure Alexei Navalny. Source: EPA
Aides have said they believe Navalny was poisoned with a cup of tea, pointing the blame at Russian President Vladimir Putin.
The Omsk regional health ministry said on Saturday that , but "no convulsive or synthetic poisons were detected".
"The suspicion is ... that somebody poisoned Mr Navalny - that somebody seriously poisoned Mr Navalny - which, unfortunately, there are some examples of in recent Russian history, so the world takes this suspicion very seriously," Mr Seibert said.
But German Foreign Minister Heiko Maas said more facts were needed before they could determine whether Mr Navalny was poisoned.
“Many facts are missing in the case of Navalny: medical and also likely criminological,” he said during a news conference in Kyiv. “We must wait for those [facts]."
Mr Navalny was flown to Berlin on a plane chartered by the German NGO Cinema for Peace, an initiative financed by private donations.
The transfer came after , saying news of Mr Navalny's condition had "truly upset" her.
