"As far as French intelligence services and military intelligence are concerned, in a matter of days we will prove that the regime has indeed organized these strikes with chemical weapons", Ayrault said.
The US responded to the attack by launching air strikes on a Syrian military airfield. A senior military official told AP Israeli military intelligence estimates that Assad has "between one and three tons" of chemical weapons.
The finding was based on tests on bio-medical samples collected from three victims during their autopsies that were analysed at two OPCW-designated laboratories, the OPCW said. Iraqi military officials said it was launched by the Islamic State group (ISIS). Syria began developing chemical weapons in the 1980s with the aim of using them against enemy states, including its neighbor Israel.
The governing body of the global chemical arms watchdog will Thursday vote on a controversial Russian-Iranian move to set up a new team to probe a suspected chemical attack in Syria, sources said.
The United States and many other nations have called the attack a chemical weapons attack and accused the Syrian government of responsibility.
While the amounts of chemical weapons Assad kept weren't known, OPCW continued reporting on the use of chemical weapons by the regime, even some which Assad had pledged to surrender.
Israel closely monitors the civil war in Syria, a northern neighbour. During the six-year conflict, Israel has largely stayed on the sidelines, carrying out occasional air strikes against what it says is the movement of weapons to Iranian-backed Lebanese Hezbollah militants.
Syria agreed to give up its chemical weapons arsenal to avert US strikes in September 2013, following a chemical weapons attack in the Damascus suburbs in August that year that killed hundreds of people and sparked worldwide outrage. However, doubts soon emerged over whether all of the regime's armaments or production facilities were declared and destroyed.
"One ton of sarin could easily be used to perpetrate an attack on the scale of the 2013 attack", Kaszeta said.
The attack April 4 on the town of Khan Sheikhoun killed more than 90 people and left hundreds more suffering from effects of the gas.
And the British delegation to the OPCW said in a tweet that Wednesday's talks showed "once again clear support for the ongoing FFM investigation into the attack".