Britain oversaw the sale of chemicals to Syria that were eventually used in the manufacture of the deadly nerve agent sarin, it has been reported.
Documents from the Foreign Office suggest chemicals and components were supplied to Syria in the mid-1980s, the BBC said.
Ministers are reportedly set to confirm that a number of UK firms provided the materials and that Syria has admitted they played a role in its chemical weapons programme.
They will also suggest there were no proper regulations at the time, but that tighter rules and controls exist now, the BBC said.
A report by UN chemical weapons inspectors found “clear and convincing evidence” that rockets containing sarin were fired at suburbs near the capital Damascus last August in an attack that killed hundreds of people.