The six-page French document - drawn up by France's military and foreign intelligence services and seen by said it reached its conclusion based on samples they had obtained from the impact strike on the ground and a blood sample from a victim.
"We know, from a certain source, that the process of fabrication of the samples taken is typical of the method developed in Syrian laboratories," Foreign Minister Jean-Marc Ayrault told reporters after presenting the findings to the cabinet.
"This method is the signature of the regime and it is what enables us to establish the responsibility of the attack. We know because we kept samples from previous attacks that we were able to use for comparison."
Among the elements found in the samples were hexamine, a hallmark of sarin produced by the Syrian government, according to the report.
It said the findings matched the results of samples obtained by French intelligence, including an unexploded grenade, from an attack in Saraqib on April 29, 2013, which Western powers have accused the Assad government of carrying out.
"This production process is developed by Syria's Scientific Studies and Research Center (SSRC) for the regime," the report said.
The United States on Monday blacklisted 271 employees belonging to the agency.
Syria agreed in September 2013 to destroy its entire chemical weapons program under a deal negotiated with the United States and Russia after hundreds of people were killed in a sarin gas attack in the outskirts of the capital, Damascus.
The report said that based on its assessments, there were "serious doubts on the accuracy, completeness and sincerity of the dismantlement of Syria's chemical arsenal."There are of course holes aplenty in this. Where is proof of the chain of custody showing the sample came from the purported Khan Sheikhoun impact crater? Otherwise, we are once again being asked to take on faith that an intelligence agency that seeks to subvert a sovereign state is in this instance acting in an objective, impartial manner.
Also, none of the by now well-circulated Postol analysis is engaged with in the slightest -- that the sarin was not distributed by a missile dropped from a plane but a device detonated on the ground; that the alleged impact crater could not have been the site for the sarin dispersal because after-incident photos showed bare-faced rescue workers handling dead birds. If sarin had been present these men would have died.
The importance of the French intelligence report is the last paragraph above, the one in red. The soil is being tilled for another false-flag sarin attack. The argument is that despite what the OPCW said, Syria still retains a sarin stockpile, and it will use it until the West bombs it out of existence.