Britain accuses Russia of secretly stockpiling deadly nerve agent used in attack

Britain's Foreign Secretary Boris Johnson is seen appearing on the BBC's Andrew Marr Show in this photograph received via the BBC in London, Britain March 18, 2018. Jeff Overs/BBC/Handout via REUTERS

LONDON (Reuters) - British Foreign Secretary Boris Johnson said on Sunday that Russia has been stockpiling the deadly nerve agent used to poison a Russian former double agent in England and has been investigating how such weapons can be used in assassinations.

Britain has said Russia used the Soviet-era nerve agent called Novichok to attack Sergei Skripal and his daughter Yulia in the first known offensive use of such a weapon on European soil since World War Two. Russia has denied any involvement.