The vote came as bombs continued to be dropped on Eastern Ghouta, the rebel-held suburb outside the capital of Damascus. More than 520 people have been killed and 2,500 have been wounded in the fighting in the last week, according to Médecins Sans Frontières.
The UN Secretary General António Guterres had called for a ceasefire earlier this week, warning that “a human tragedy is unfolding in front of our eyes [with] 400,000 people living in hell on earth".
The Security Council resolution calls for the fighting to stop "without delay" so that emergency aid supplies can be delivered and the injured evacuated. The vote was delayed by several days, as delegates said Russia – an ally of Syrian President Bashar al-Assad's – refused to a agree to a proposal.
Russian ambassador Vassily Nebenzia had called the motion “unrealistic” and accused other council members of being misled by a “massive psychosis”. The country – which provides military support to Mr Assad's forces – agreed to the resolution on Saturday, after a requirement that the ceasefire be implemented in 72 hours was dropped.
US Ambassador to the UN Nikki Haley criticised Russia for "stalling" the vote on Friday. In a speech after Saturday's vote, she said the council as "very late" in taking action.
"In the three days it took us to adopt this resolution, how many mothers lost their kids to the bombing?" she asked.
The bombings in Eastern Ghouta this week have overwhelmed hospitals and left residents with little food or medical supplies. More than 22 medical facilities have been damaged in some of the worst violence seen since the start of the civil war seven years ago, according to Syrian activists.
The country's civil defence rescue service, known as the White Helmets, said it was difficult to get an accurate count of the number of dead and injured because of the relentless bombardment.
“Maybe there are many more,” Siraj Mahmoud, a spokesman for the group told Reuters. “We weren’t able to count the martyrs yesterday or the day before because the warplanes are touring the skies.”
An estimated 400,000 people live in Eastern Ghouta. The government claims they are firing on al-Qaeda-linked groups in the area and only targeting militants.
Rebels responded by firing mortar shells at Damascus on Saturday, killing at least one person and injuring seven, according to Syrian state media.
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