Input: Relationship: 'report to', Argument/Subject 1: 'secretary-general', Argument/Subject 2: 'security council'

Answer: In the absence of conclusive evidence of the weapons used , it could not be determined how the injuries were caused .UN Security Council , Report of the Mission Dispatched by the Secretary-General to Investigate Allegations of the Use of Chemical Weapons in the Conflict Between the Islamic Republic of Iran and Iraq , S/18852 .