The United Nations is launching an investigation into allegations of a chemical weapons attack near the Syrian city of Aleppo. Both the Syrian government and rebels had called for a U.N. probe with each accusing the other of carrying out an attack. So far no evidence has emerged chemical weapons were actually used. U.N. Secretary-General Ban Ki-moon announced the U.N. inquiry Thursday.

Ban Ki-moon: “The investigation mission is to look into the specific incident brought to my attention by the Syrian government. I am, of course, aware that there are other allegations of similar cases involving the reported use of chemical weapons. My announcement should serve as an unequivocal reminder that the use of chemical weapons is a crime against humanity.”