The German government says it now has "unequivocal proof" that the Russian opposition leader Alexei Navalny was poisoned with a Novichok nerve agent.
Navalny was airlifted to Berlin for treatment last month after falling ill during a flight in Siberia and he has been in a coma ever since.
German Chancellor Angela Merkel says the case raises serious questions that only the Russian government can answer.
RNZ correspondent in Berlin is Thomas Sparrow.
