French President Emmanuel Macron has threatened to “strike” Syria if proof emerges that its government is using chemical weapons against civilians.
But Mr Macron said French intelligence had so far found no evidence that banned chemical weapons had been used.
His comments follow numerous reports of suspected chlorine attacks in Syria since early January.
Nine people were treated for breathing difficulties after a bomb believed to be filled with the chemical was dropped on a rebel-held town earlier this month.
The Syrian opposition said a government helicopter dropped the bomb on Saraqeb, in the north-western province of Idlib.