UN weapons inspectors have been continuing to collect samples and interview witnesses and victims following last week's alleged chemical attack near Damascus.
Ban Ki-moon has urged the international community to let the inspection team "do their job" before deciding whether or not to pursue potential military action against the Assad regime.
The prospect of a US and UK military intervention in Syria appears increasingly likely, but what would an attack by western forces involve?
A textile factory in Damascus has started producing gas masks in case of a repeat of a suspected chemical attack on the area.
Western countries including the UK are considering their response to Syria as evidence of a large-scale chemical attack in Damascus mounts.