French President Emmanuel Macron stressed on Friday concerns about the deterioration of the situation in Syria in a phone call with his Russian counterpart Vladimir Putin and called for more dialogue with Moscow.

Macron, who on Thursday said France had proof the Syrian regime used chemical weapons in an attack last week, also expressed regret at Russia’s use of its United Nations Security Council veto on the attack.

“The president of the republic called for dialogue with Russia to be maintained and stepped up to bring peace and stability back to Syria,” a statement from Macron’s office said.