Navalny poisoned with dart frog toxin, say UK and allies

It is not clear how the frog poison - called epibatidine - was allegedly administered to Mr Navalny, who had been in a penal colony in Siberia when he died almost exactly two years ago.

Indigenous tribes in South America are said to use the toxin in blow darts or blowguns when they hunt.

The poison is 200 times stronger than morphine.

Yulia Navalnaya, the Russian dissident's widow, appeared at a press conference on the sidelines of a security conference in Munich to announce the discovery, flanked by the foreign ministers of the UK, Germany, Sweden and the Netherlands.

The four countries and France have been working together to establish how Mr Navalny, 47, died.