The UN special envoy for Syria, Staffan de Mistura, said that no aid convoys had reached besieged areas of Syria for the past month, and that he had suspended a humanitarian task force until next week as a signal to major powers.
The envoy re-issued the UN's call for a weekly 48-hour humanitarian pause in Aleppo, where an estimated 1.5 million civilians are trapped as fierce fighting rages between Syria President Bashar al-Assad's forces and rebels.
The envoy says he plans to reconvene the task force next week, and believes its co-chairs - Russian Federation and the United States - still want a nonmilitary solution to Syria's conflict.
Russia's General Staff later said that combat operations in Aleppo would be paused each day for three hours to let humanitarian convoys reach the city's center.
De Mistura spoke after suspending the weekly meeting of the humanitarian task force after eight minutes "as a sign of deep unhappiness" with the failure to restore calm to enable aid deliveries to stricken civilians in besieged districts.
Meanwhile, Syrian government warplanes bombed Kurdish-controlled areas of the city of Hasaka in northeastern Syria yesterday for the first time in the five-year-old civil war, the spokesman for the Syrian Kurdish YPG militia and a monitoring group said.
He also urged "all those with access to or influence on the armed opposition, in particular the United States.to ensure that the armed opposition also respects the 48-hours humanitarian pause".
He welcomed the Russian defense ministry announcement and said the United Nations humanitarian team "is now set to mobilize itself to respond to this challenge".
Deir Ezzor, which is partially controlled by the so-called Islamic State group, has continued to receive aid over the last month through World Food Programme air drops, Mr de Mistura said.
He says aid could be sent from Gaziantep in Turkey to the eastern part of Aleppo via Castello road.
The image of the stunned and weary-looking boy, sitting in an orange chair inside an ambulance, covered in dust and with blood on his face, encapsulates the horrors inflicted on the war-ravaged northern city.