The Organization for the Prohibition of Chemical Weapons (OPCW) reported that the delegation, sent to investigate Syria's chemical attack in the Douma province, could not cross the border for security reasons.
The delegation, consisting of nine experts, have not yet allowed by Russia and Syria to access to Douma.
The OPCW delegation went to Syria last week to investigate the chemical attack that carried out in the Douma district of Eastern Ghouta on April 7, where dozens lost their lives and more than a thousand people wounded.
OPCW still has the authority to investigate suspected chemical attacks in Syria. The investigation team will determine whether banned weapons have been used.
ILKHA