Suffering in Syria has reached "unprecedented" levels, the United Nations has said after a series of deadly airstrikes.
At least 80 people were killed on Tuesday in government air and artillery strikes on besieged areas of the capital Damascus.
The bombing was one of the bloodiest in the eastern Ghouta region for over a month.
Images of blood-soaked children and adults competed with video of rescuers carrying white body bags or pulling survivors from the debris of destroyed homes after the strikes.
UN officials have now called for a month-long ceasefire to deliver critical humanitarian aid to civilians across the country.
Blocked access to aid in three major urban areas, growing displacement and more than 13 million people in need are adding to the humanitarian crisis, according to the UN.
The organisation said the situation had reached "extreme" levels which "we haven't seen before".
Syria's civil war has been ongoing for eight years and has been marked by a mass exodus of Syrian citizens and the death toll surpassing 500,000 in 2016.
Meanwhile the lead investigator of a UN-mandated Commission of Inquiry said that spiraling violence in the country had made "a mockery of the so-called 'de-escalation zones'"
Paulo Pinheiro described the government's siege and indiscriminate bombardment of eastern Ghouta as "international crimes".