Updated

The U.N. Security Council says it is gravely concerned at reports of alleged chlorine gas use in some Syrian towns, which caused deaths and injuries, and is calling for an investigation.

Nigeria's U.N. Ambassador U. Joy Ogwu, the current council president, told reporters that the alleged chlorine gas attacks were raised during a closed-door council meeting following a video briefing Wednesday by Sigrid Kaag, who heads the mission charged with destroying Syria's chemical weapons.

She said council members called for an investigation but did not discuss who should carry it out. She suggested that the Organization for the Prohibition of Chemical Weapons, which Syria joined last year, could play a role.

Syria's U.N. Ambassador Bashar Ja'afari said his government "denies categorically the use of chlorine gas by the Syrian army."