UN chemical weapons experts in Syria
UN chemical weapons experts in Syria Reuters

Syria's Foreign Ministry in a Saturday statement said the Organization for the Prohibition of Chemical Weapons should prepare "impartial and credible reports that have not been subjected to extortions by countries and parties that prevent it from reaching the truth."

The current probe, they said, is "the creation of a sick mind," relies on "terrorists'" testimony, and is utterly false.

The report, which was released on Friday, confirmed the use of sarin gas in the Khan Sheikhoun attack on April 4, which killed 90 people. It did not, however, state for certain who was responsible for the use of chemical weapons.

OPCW Director-General Ahmet Uzumcu told AP in a statement, "I strongly condemn this atrocity, which wholly contradicts the norms enshrined in the Chemical Weapons Convention."

"The perpetrators of this horrific attack must be held accountable for their crimes."

Meanwhile, Assad has denied using chemical weapons and has even claimed that the Khan Sheikhoun attack was fabricated by the United States.