The French foreign minister has said that France's intelligence services have evidence that the Syrian government carried out the alleged chemical weapons attack on a rebel village earlier this month.
"There is an investigation underway... it's a question of days and we will provide proof that the regime carried out these strikes," Jean-Marc Ayrault said in a statement.
The suspected attack on Khan Sheikhun was found by British and Turkish scientists to have involved both sarin, a nerve gas, and chlorine.
Syrian President Bashar al-Assad has repeatedly denied his government has any chemical weapons stocks after agreeing to give them up to international monitors in 2013.
The Organisation for the Prohibition of Chemical Weapons (OPCW) has said it believes Mr Assad's government is responsible for at least two chemical weapons attacks that have occurred in Syria since then - claims the president also denies.