Syrian opposition activists have posted photographs and video that they say shows an improvised chlorine bomb to back up claims that President Bashar al-Assad's forces used chemical ******* in two attacks last week. Both sides said chlorine gas - a deadly agent widely used in World War I - had been used. The gas, which has industrial uses, is **t on a list of chemical ******* that Assad declared to the global chemical ******* watchdog last year for destruction. Eliot Higgins, a respected UK-based researcher who trawls daily through online videos of Syria's civil war to verify ******* in them, could **t verify the opposition's claims but said the videos did appear to show an industrial chlorine cylinder.