The recent attacks, near Damascus, appear to have involved Sarin.
Sarin has extreme potency as a nerve agent and production and stockpiling of sarin was outlawed by the Chemical Weapons Convention of 1993 where it is classified as a Schedule 1 substance.
As at 21st May 2009, Syria had not signed or acceded to the Chemical Weapons Convention - see OPCW - though Syria was a party to the 1925 Geneva Gas Protocol. There is some authority that the use of chemical weaponry is unlawful under customary international law.
Law and Lawyers 31st August - House of Commons debate on Syria 29th August
Organisation for the Prohibition of Chemical Weapons
OPCW 31st August - UN Investigation Team return to The Hague from Syria
UN Office for Disarmament Affairs - Chemical Weapons
UN Office for Disarmament Affairs
Statement of Foreign Secretary (William Hague) 23rd August 2013.
Sales of chemicals to Syria:
The Guardian 2nd September - Chemical export licences for Syria - just another UK deal with a dictator
Update --- Syria and the Chemical Weapons Convention:
Syria is to accede to the Chemical Weapons Convention - HERE.
14 September 2013
13 September 2013