LONDON, Sept 6 —Russia must explain how Kremlin critic Alexei Navalny was poisoned with what Germany says was the Novichok nerve agent, British foreign minister Dominic Raab said today.

“What is clear right now is that the Russian government has a very serious set of questions to answer,” he told Sky News.

Whether the incident involved a state actor or not, Russia had obligations to make sure that chemical weapons cannot be used on its soil, Raab said. — Reuters