UN Secretary-General Ban Ki-moon said on Thursday that all warring parties in Syria should fully cooperate with a new international inquiry into who has been responsible for chemical weapon attacks during the civil war in the country.
Ban’s remarks were sent in a letter to the UN Security Council in which he put forward a programme for investigating alleged poison gas attacks by both the Syrian regime and rebel groups in the four-year-long war.
The investigation will be conducted by the United Nations and Organization for the Prohibition of Chemical Weapons (OPCW).
"Success will ... depend on the full cooperation from all parties, including the Government of the Syrian Arab Republic and other parties in Syria," Ban said in the letter, according to Reuters.
The inquiry, which will be chaired by an assistant secretary-general and two deputies, aims "to identify to the greatest extent feasible individuals, entities, groups, or governments who were perpetrators, organizers, sponsors or otherwise involved in the use of chemicals as weapons, including chlorine or any other toxic chemical," he added.
Ban said earlier on Thursday in a statement that "continuing reports of the use of chemical weapons, as well as the use of toxic chemicals as a weapon in the Syrian conflict are deeply disturbing."
Ban's letter came in response to the Aug. 7 adoption of a resolution by the Security Council which called for an investigation into the use of toxic chemicals in Syria.
The chairman of the investigation has not yet been named but the council is expected to respond to Ban within five days. The investigation is planned to have a one-year mandate which may be renewed.
The Syrian government and opposition forces have both denied using chemical weapons.
The army of Syrian President Bashar al Assad has been constantly accused by the United Kingdom, France and the United States of carrying out chemical attacks and barrel bomb strikes on innocent civilians, including women and children.
However Moscow has protected the Syrian regıme from such accusations, claiming that there is no evidence that it was behind the attacks.
The Security Council faced extreme pressure to take binding action, as the Syrian conflict enters its fifth year.
The Assad regime has been accused of repeatedly used toxic chemical weapons, including in Ghouta in 2013, in attacks which have claimed the lives of 1,300 Syrians.
In 2013, Syria agreed to destroy its chemical weapon stockpiles in to avoid military strikes by the US following a sarin gas attack that killed hundreds of civilians. The Syrian Network for Human Rights had previously published a report concerning Assad’s usage of poisonous gas in attacks against Syrians, accusing Assad of breaking Security Council resolution number 2118 issued in December 2013 which forbids the use of poison gases in Syria.
The OPCW has since found that chlorine has been "systematically and repeatedly" used as a weapon in the Syrian conflict, though it does not have the authority to lay blame.
The usage of chlorine gas as a weapon is prohibited under the 1997 Chemical Weapons Convention, which Syria joined in 2013. If chlorine gas is inhaled it turns into hydrochloric acid in the lungs and is capable of killing the victim.
According to the UN, the four-year-long war in Syria has left more than 250,000 people dead and 6.7 million internally displaced, while at least 5.4 million others have fled the country.