Prime Minister Stephen Harper says he is now convinced Syrian President Bashar Assad has used chemical weapons against the country’s rebel forces, adding his voice to a growing chorus of international leaders slamming the Syrian leader.

Harper made the remarks in France, where he is meeting with French President Francois Hollande to discuss a Canada-Europe free trade pact.

The U.S. had announced Thursday it now has conclusive proof Assad has used chemical weapons, including the nerve-agent sarin, against opposition forces.