- Video report by ITV Correspondent Dan Rivers and ITV News Journalist Jonathan Wald
International chemical weapons inspectors have collected samples of soil and human tissue from the Syrian town of Douma in an effort to establish if such weapons were used by President Assad's forces in an attack there.
On Monday ITV News Correspondent Dan Rivers was taken, by regime minders, to the hospital where those who were affected by the attack were treated.
Accounts heard by ITV News gave conflicting stories about what exactly happened during the attack, which took place two weeks ago.
The atrocities in Douma triggered retaliatory strikes by Western powers on the Syrian government's chemical facilities.
Britain, America and France say the regime used chemical substances, most likely chlorine and sarin, that medical workers said killed more than 40 people.
The Syrian government and its ally Russia denied responsibility for the attack.
Images emerged in the hours after the attack showing lifeless bodies collapsed in crowded rooms, some with foam around their noses and mouths.
Adnan Jarkas, a nurse who was present at the hospital when the attack took place, told ITV News under Government supervision: "We saw a civilian man bringing in his daughter in and shouting gas, gas and then he just disappeared.
"After that the white helmets came in bringing people, it was chaos that's all that happened.
"Most of the case were asthma and no chemical attack that day."
However, some of the staff from the hospital in Douma fled to northern Syria where they told a British-Syrian doctor those who stayed were pressured by the regime to change their story about the attack.
Dr Ghnem Tayara told ITV News: "They were put under enormous pressure, the situation there is a matter of life or death for them.
"If you don't comply with what the regime want then you can lose your life."
The Organisation for the Prohibition of Chemical Weapons said in a statement that it visited "one of the sites" in Douma to collect samples for analysis at agency-designated laboratories, adding it would "consider future steps including another possible visit to Douma."
It said the mission will draft a report based on the findings, "as well other information and materials collected by the team."
The OPCW mission is not mandated to apportion to blame for the attack.