The regime of President Bashar Assad had enough of nerve gas sarin to “eradicate the whole of Damascus, Homs, Hama and Aleppo,” a former Syrian chemical weapons scientist told Al Jazeera on Friday.

“If the regime is to fire a Scud-B with a chemical warhead filled with sarin, the missile would create a chemical cloud in the atmosphere that is 3km long and 500m wide, which could be fatal to all people under it,” the scientist, that asked to remain anonymous, said.

The scientist told Al Jazeera that Syria’s chemical weapons stockpile includes 700 tons of sarin gas as well as mustard gas in unspecific quantity, at least 3,000 aerial bombs that could be fitted with chemical warheads and more than 100 chemical warheads for Scud missiles. He dispelled assessment by Western intelligence that Syria has tabun nerve gas.