At the start of that meeting the UN's top envoy to Syria accused the government of unleashing "unprecedented military violence" against civilians in Aleppo.
Staffan de Mistura said Syria's declaration of a military offensive to retake rebel-held eastern Aleppo has led to one of the worst weeks of the 5 1/2-year war with dozens of airstrikes against residential areas and buildings causing scores of civilian deaths.
Medical workers and local officials reported airstrikes on neighborhoods throughout Aleppo's rebel-held eastern districts as an announced government offensive entered its fourth day.
The Britain-based Syrian Observatory for Human Rights reported 23 civilians had been killed by 6 pm and said it expects the toll to rise.
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Ibrahim Alhaj of the Syrian Civil Defence search and rescue outfit said hospitals and rescuers have documented the deaths of 43 people so far.
Hospitals are overwhelmed with casualties and medical workers are expecting many of the wounded to die from a lack of treatment, according to Mohammad Zein Khandaqani, a member of the Medical Council, which oversees medical affairs in the opposition areas.
The Observatory, which relies on a network of contacts inside Syria, said earlier in the day that 213 civilians have been killed by airstrikes and shelling on opposition areas in and around Aleppo since a US-Russian brokered cease-fire collapsed Monday evening.
De Mistura, at the Security Council meeting, warned that if the Syrian government is intent on taking Aleppo, it is going to be "a grinding" a street-by-street fight where all the infrastructure in the city will be destroyed, but it won't lead to victory.
He urged the United States and Russia to go "that extra mile" and save the September 9 cessation of hostilities agreement "at the 11th hour.