The United Nations has condemned the failure of both the Syrian government and rebel forces in Eastern Ghouta to observe several attempts at ceasefires, calling the besieged Damascus suburb “devoid of respect for international law”.

Thursday saw a third day of Russian-brokered pauses in fighting come to naught. Locals and war monitors reported continued air strikes and shelling on the area’s towns and farms throughout the day, as well as shelling of humanitarian corridors leading out of the area.

Both sides blamed the other for the violence. The Russian defence ministry said that rebel shelling of the corridors, supposed to allow medical evacuations out and aid deliveries in, had killed four civilians.

Boris Johnson suggests the UK could strike Syria in response to Assad's attack on eastern Ghouta

Dr Hamza Hassan, an ear, nose and throat specialist working in Eastern Ghouta, told The Independent that people were afraid of both the gunfire and shelling preventing people from leaving the district, and of what may await them on the other side.

“Why would you leave your home for something unknown, maybe a tent, on the other side where they are trying to kill you?” he said.

Syrian President Bashar al-Assad’s 12-day-old assault on one of the last rebel strongholds has now killed more than 600 people in one of the bloodiest operations in the seven-year-old war to date.

A rare unanimous UN Security Council resolution passed on Saturday demanding an immediate cessation in hostilities made no significant difference to the violence, nor did Syrian ally Russian President Vladimir Putin’s order on Monday for daily five-hour pauses.

“You are failing to help us help civilians in Syria,” UN humanitarian adviser Jan Egeland told diplomats from 23 states attending a weekly meeting in Geneva on Thursday, urging member states to help the UN expand the humanitarian windows in which waiting trucks of aid could be delivered.

“Eastern Ghouta is devoid of respect for international law.”

Eastern Ghouta bombings: Syrian war in pictures Show all 14 1 /14 Eastern Ghouta bombings: Syrian war in pictures Eastern Ghouta bombings: Syrian war in pictures A Syrian woman and children run for cover amid the rubble of buildings. AFP/Getty Eastern Ghouta bombings: Syrian war in pictures Smoke rises from buildings following the attack on the village of Mesraba in the rebel-held besieged Eastern Ghouta region on the outskirts of the capital Damascu. AFP/Getty Eastern Ghouta bombings: Syrian war in pictures Injured children receive medical treatment. EPA Eastern Ghouta bombings: Syrian war in pictures A Syrian man carries a child injured. AFP/Getty Eastern Ghouta bombings: Syrian war in pictures An injured child receives treatment following bombings on several areas of eastern Ghouta. EPA Eastern Ghouta bombings: Syrian war in pictures A child reacts inside a hospital after relatives were injured in the bombing. EPA Eastern Ghouta bombings: Syrian war in pictures Syrian children cry at a make-shift hospital in Douma following air strikes on the Syrian village of Mesraba. AFP/Getty Eastern Ghouta bombings: Syrian war in pictures Syrian Civil Defense group extinguishing a store during airstrikes and shelling by Syrian government forces. AP Eastern Ghouta bombings: Syrian war in pictures A wounded 12-year-old Syrian boy, cries as he receives treatment at a make-shift hospital. AFP/Getty Eastern Ghouta bombings: Syrian war in pictures Syrians carry a wounded man. AFP/Getty Eastern Ghouta bombings: Syrian war in pictures An injured man covered with blood at a medical point. Reuters Eastern Ghouta bombings: Syrian war in pictures People sit a medical point in the besieged town of Douma, Eastern Ghouta. Reuters Eastern Ghouta bombings: Syrian war in pictures Syrian Civil Defense running to help survivors. AP Eastern Ghouta bombings: Syrian war in pictures Injured children receive medical treatment. EPA

UN officials hope to create a two-way corridor to allow civilians to leave, and permit weekly deliveries of humanitarian aid.

Ghanem Tayara, chair of the Union of Medical Care and Relief Organisations working across Syria, said some 1,123 patients needed to be evacuated from Eastern Ghouta for emergency reasons. At least 24 medical facilities in the area have been damaged in air strikes – bombings the UN warned could constitute war crimes.

“The UN resolution has been ignored completely,” he said.

British officials have asked the UN Human Rights Council in New York for an urgently scheduled debate to address the failed efforts to establish a ceasefire.

The UN’s envoy to Syria, Staffan de Mistura, warned that the international community must actively seek a lasting solution.

“We cannot afford to have the luxury of giving up. So any type of feeling that the UN is frustrated: forget it.

“Otherwise, [the Eastern Ghouta assault] becomes a copycat of Aleppo,” he said.

The siege of Aleppo ended in December 2016 after a massive Russian-backed bombing campaign. Civilians and rebel fighters were bussed out of the city to the neighbouring opposition-held province of Idlib.

The government’s tactics echo several other urban battles in Syria’s complex conflict. Approximately 400,000 people have lived under siege in Eastern Ghouta since 2012, the UN says, and food and medical supplies are running low.

While Eastern Ghouta is technically covered by a 2017 de-escalation deal, Mr Assad says he is targeting al-Qaeda-linked factions in the area not covered by the agreement.