The United Nations high commissioner for human rights says Syria and its allies, Russia and Iran, have almost certainly violated international law and probably committed war crimes by bombing civilians hoping to be evacuated from eastern Aleppo.
UN human rights chief Zeid bin Ra’ad Zeid al-Hussein made the accusations in a December 14 statement issued after a purported Aleppo evacuation plan announced by Russia a day earlier failed to materialize.
Zeid said he was "appalled that the deal enabling the evacuation of many thousands of civilians, including the wounded and the sick, from the remaining opposition-held area of eastern Aleppo appears to have collapsed."
Zeid acknowledged that the reasons for the breakdown of the cease-fire were disputed, but said that "the resumption of extremely heavy bombardment by the Syrian government forces and their allies on an area packed with civilians is almost certainly a violation of international law and most likely constitutes war crimes."
He also said the Syrian government "has a clear responsibility to ensure its people are safe, and is palpably failing to take this opportunity to do so."
Late on December 13, Russian UN Ambassador Vitaly Churkin said an agreement had been struck for rebel fighters and civilians to be safely evacuated from eastern Aleppo.
Churkin told an emergency session of the UN Security Council that military activities in eastern Aleppo had stopped and that the Syrian government had "established control" over the area.
But fierce fighting, air strikes, and artillery barrages shattered the purported cease-fire deal less than 12 hours later before any evacuation materialized.
The British-based Syrian Observatory for Human Rights confirmed there was shelling, air strikes, and "very intense clashes on every front line" between Syrian government forces and rebels in Aleppo.
The Russian Defense Ministry said that government forces resumed their assault after rebels, in the ministry's words, broke the truce brokered by Turkey and Russia.
'Fragile And Complicated'
But in Ankara, Turkish President Recep Tayyip Erdogan accused Syrian government forces of breaking the deal.
Erdogan's comments came after Turkish Foreign Minister Mevlut Cavusoglu accused Syrian President Bashar al-Assad's government and its allies of trying to intentionally scuttle the agreement.
"We see now that the regime and other groups are trying to obstruct this [deal]," he said. "This includes Russia, Iran -- forces supported by Iran -- and the [Syrian] regime."
Later on December 14, officials in Turkey's presidential office said Erdogan and Russian President Vladimir Putin agreed in a telephone conversation to make a joint effort to start the evacuation of civilians and opposition forces from eastern Aleppo as soon as possible.
Reuters quoted the Turkish presidential sources as saying that both Erdogan and Putin agreed on the need to prevent further cease-fire violations
German government spokesman Steffen Seibert said Russia was partly responsible for the destruction of eastern Aleppo.
"We know that this ruthless destruction of eastern Aleppo would not have been possible without massive military support from Russia," Seibert said. "Russia has not prevented the crimes of the last few days although it was within its power to do so."
Assad has been backed by Russian air strikes and an array of Shi'ite militias from Iran and Lebanon in his campaign to seize full control of Aleppo, which was the most populous city in Syria before the more than 5-year-old civil war.
In excerpts from an interview aired on December 14 by state-funded Russian channel RT, Assad accused Western countries of seeking a cease-fire in Aleppo to "save" what he called "the terrorists" -- a reference to rebels fighting against his government.
Meanwhile, Russian Foreign Minister Sergei Lavrov said he expected rebel resistance in eastern Aleppo to end "in the next two to three days."
WATCH: U.S. Attacks 'Shameless' Aleppo Assault
The Russian Defense Ministry claimed on December 14 that nearly 6,000 civilians had left Aleppo's rebel-held districts during the previous 24 hours.
It also said that 366 rebels had laid down their arms over the same period and moved out of rebel-controlled parts of the city.
But the UN human rights office said it was receiving reports of pro-government forces in Syria entering homes in eastern Aleppo and shooting civilians dead "on the spot."
The UN human rights office said on December 13 that it had reliable evidence from four Aleppo neighborhoods that 82 civilians, including 11 women and 13 children, had been summarily executed.
Spokesman Rupert Colville said the atrocities were committed in recent days, adding that there could have been "many more" execution-style killings.
UN humanitarian spokesman Jens Laerke said it looked like "a complete meltdown of humanity in Aleppo."
Syria's UN ambassador, Bashar al-Ja'afari, denied allegations of any mass killings or revenge attacks and insisted that it was Syria's "constitutional right" to go after what he called terrorists.
"Aleppo has been liberated from terrorists and those who toyed with terrorism," Ja'afari said. "Aleppo has returned to the nation."
U.S. Ambassador Samantha Power said the Syrian government, Russia, and Iran bore responsibility for “the conquest of and carnage in Aleppo.”
"Aleppo will join the ranks of those events in world history that define modern evil, that stain our conscience decades later,” Power said, citing the 1988 Halabja chemical attack in northern Iraq, the 1994 Rwandan genocide, and the 1995 Srebrenica massacre during the Bosnian war.