A report by UN chemical weapons experts will likely confirm that poison gas was used in an Aug. 21 attack on Damascus suburbs that killed hundreds of people, UN Secretary-General Ban Ki-moon said on Friday.

"I believe that the report will be an overwhelming, overwhelming report that chemical weapons (were) used even though I cannot publicly say at this time before I receive this report," Ban said at a UN meeting.

He was referring to a report by the UN expert team led by Ake Sellstrom of Sweden.

Ban also said that Syrian President Bashar al-Assad "has committed many crimes against humanity," though he did not say whether it was Assad's forces or rebels who used chemical toxins in the Aug. 21 attack.