UN report to confirm chemical arms attack
14 September 2013 Last updated at 02:01 BST
A UN report expected next week will "overwhelmingly" confirm that chemical weapons were used in Syria last month, the secretary general says.
Ban Ki-moon made no comment on who was to blame for the 21 August attack in the Ghouta area of Damascus, as that is not part of the report's remit.
But he did say Syria's President Assad was guilty of "crimes against humanity".
The US and Russian foreign ministers are continuing their talks on a plan to make safe Syria's chemical weapons.