Speaking after briefing the Security Council on the peace process, Staffan de Mistura said a partial truce agreed in February was "barely alive".<br />Violence in Syria has intensified in recent days, despite the ceasefire.<br />At least 20 civilians were reportedly killed on Wednesday in government strikes on a hospital and nearby residential building in eastern Aleppo.<br />The upsurge in fighting in Syria's largest city comes amid reports that government forces, backed by Russian air power, are gearing up for a major offensive there.<br />Calling on the US and Russia to co-operate, Mr de Mistura said that the legacies of both President Barack Obama and President Vladimir Putin were linked to the success of the peace process in Syria.
