A general view taken with a drone shows Aleppo's historic citadel, controlled by forces loyal to Syria's President Bashar al-Assad, as seen from a rebel-held area of Aleppo, Syria, October 12, 2016. [Photo/Agencies]

Syrian President Bashar al-Assad's forces "propped up by Russia and Iran, have once again redefined horror. They have gone from siege to slaughter," he said.

He said that the United Nations had received reports that pro-government forces were entering homes in eastern Aleppo, "going door to door, executing people on the spot; 82 people murdered, 13 of whom were women, 11 were children. None were terrorists. We have heard reports of women committing suicide, in order not to be raped."

The UK envoy, listing additional atrocity reports, added, "All these reports evoke the darkest days of the history of the United Nations. So, re-find your moral compass."

New Zealand's Ambassador Gerard van Bohemen also appeared moved, repeatedly rapping his knuckles on the desk calling this his "Rwanda moment," referring to the UN's failure to stop the genocide in Rwanda 23 years ago.

"I choose to believe the secretary-general when he comes to this council and tells us there are credible reports of atrocities being committed," particularly, "when they say the issue is not terrorism, but it is barbarism," van Bohemen said.

Ambassador Wu Haitao, China's deputy permanent representative to the United Nations, was more leveled.

"The international community should ponder in-depth the underlying causes of the current situation and adopt integrated measures in search of comprehensive, fair and proper solution," he said.

"Given the complexity and sensitivity of current circumstances, it is all the more important for the international community to stay the course without wavering towards our overarching goal," Wu said. "That is, to seek a political settlement."

"We should work together to move the Syrian issue back to the parts of dialogue and consultation with the view to finding a once-for-all solution to the war and chaos as soon as possible," Wu said.

"Any efforts by the international community should be ... on all four tracks, namely resumption of ceasefire, political talks, joint counter-terrorism and humanitarian assistance."