Berlin hospital says Alexei Navalny was poisoned

Berlin Charite hospital said that its data indicated Alexei Navalny was probably intoxicated by a substance in the cholinesterase inhibitors group of chemicals, but that it had not yet identified a precise substance.

The effects of such a chemical on Navalny had been "shown several times and in separate laboratories," the hospital said. Cholinesterase inhibitors are found in several drugs, but also pesticides and nerve agents.

Navalny was flown to Berlin on Saturday via a German-operated flight to receive treatment and has been in a coma for several days.

''The patient is in an intensive care unit and is still in an induced coma. His health is serious but there is currently no acute danger to his life,'' Charite hospital said. Doctors are currently treating Navalny with the antidote atropine.

But doubts remain about the 44-year-old's health in the future. "The outcome of the disease remains uncertain and after effects, especially in the area of the nervous system, cannot be excluded at this time," the hospital statement read.

Berlin police and federal agents are both providing security for the Russian opposition figure at Charite hospital, which is located in downtown Berlin, Deutsche Welle reported.