French intelligence has blamed the Assad regime for the chemical attack which killed more than 70 people in the Syrian town of Khan Sheikhun earlier this month.
The conclusion is contained in a six-page intelligence document, which has now been declassified, and was based on samples taken from the site and a blood sample from one of the victims.
The investigators reportedly found hexamine, a sarin which is produced by the Damascus regime.
The report claims the attack could not have been carried out by a jihadist group, as Islamic State does not have a significant presence in the region and none of those groups that are present has the resources to carry out such a significant strike.
Investigators also believe Bashar al-Assad would have at least authorised the attack and could even have ordered it himself.
The French intelligence services consider that only Bashar al-Assad and some of his most influential entourage can give the order to use chemical weapons," the report says.
The attack on the town in the Idlib province, carried out on April 4, was universally condemned, with the US launching an airstrike on the base from which the assault was launched.