“We have a group just to deal with chemical weapons. They are already trained to secure sites,” said Gen Adnan Silou, the most senior ranking member of Bashar al-Assad’s regime to defect and join the FSA.

Until 2008 Gen Silou was charged with the task of drafting emergency response plans should any of Syria’s terrifying array of weapons fall out of the government’s control.

Working around Damascus and Latakia he trained thousands of troops in how to secure what analysts believe are the largest chemical weapons stores in the world, consisting principally of sarin, mustard gas and cyanide.

“We trained them in securing stores, in reconnaissance of possible threats, in how to purge supplies and in treatment should Syria come under attack a chemical or biological attack,” said Silou.