Porton Down chief: Russia's poison accusation 'just not true'

Russia's suggestion that poison used in the Salisbury incident came from a UK facility, is "just not true", according to the director of the military research centre at Porton Down, Gary Aitkenhead.

Scientists at the chemical defence unit have been analysing samples of the nerve agent taken after the attack, which left former Russian spy Sergei Skripal and his daughter Yulia in a critical condition.

The BBC's Gordon Corera has been give exclusive access to Porton Down.