Syrian conflict: Key sarin ingredients sold by UK firms
9 July 2014 Last updated at 16:08 BST
Britain sold chemicals and components to Syria that ended up being used in the manufacture of the deadly nerve agent sarin, BBC Newsnight can reveal.
A leaked Foreign Office document says they were supplied in the mid-1980s.
Ministers will confirm within days that UK firms provided the materials and that Syria has admitted they played a role in its chemical weapons programme.
They will say there were no proper regulations at the time, but that tighter rules and controls exist now.
Sarin has been linked to a number of attacks in Syria's bloody three-year conflict.
Newsnight's investigations correspondent Nick Hopkins reports.