Former Irish President Mary Robinson has urged the international community to take a tougher line with Russia and China over their support for the Syrian Government.
She made the call as Syrian troops continued to shell rebel positions in the city of Aleppo.
Regime forces have also resumed shelling the rebel-held town of Tal-Abyad on the border with Turkey.
Ms Robinson says China and Russia must stop blocking international efforts to end the war in Syria.
"I think it's time to take on the two countries that are blocking that - the Russian Federation and China, and have more popular criticism of those countries," she said.
"How can they be supporting a regime that is literally killing its people in very large numbers and driving them out of the country?"