Geneva: The United Nations' top human rights official said on Friday that the siege and bombing of eastern Aleppo in Syria constituted "crimes of historic proportions" that have caused heavy civilian casualties amounting to war crimes.
The UN Human Rights Council later voted to launch an independent inquiry into events in Aleppo to identify and hold accountable anyone responsible for alleged violations.
Zeid Ra'ad Al Hussein did not specifically name Russia, whose war planes have carried out weeks of air strikes on the rebel-held part of Aleppo along with the Syrian air force, but his reference was clear.
"Armed opposition groups continue to fire mortars and other projectiles into civilian neighbourhoods of western Aleppo, but indiscriminate air strikes across the eastern part of the city by government forces and their allies are responsible for the overwhelming majority of civilian casualties," Zeid said in a speech to a special session of the UN Human Rights Council.
Such violations constituted war crimes and if there was intent to commit them as part of a widespread or systematic attack against civilians, they would amount to crimes against humanity, he said.
Zeid called for major powers to put aside their differences and refer the situation to the International Criminal Court.
"The violations and abuses suffered by people across the country, including the siege and bombardment of eastern Aleppo, are simply not tragedies; they also constitute crimes of historic proportions," he told the Geneva session by video link.
Russia has denied any deliberate targeting of civilians and says it is combating terrorists. It had proposed amendments to Britain's resolution but they were voted down.
The Russian and Syrian ambassadors said that their forces were observing an 11-hour truce in Aleppo to allow evacuation of the wounded and for civilians to leave.
Britain's junior Foreign Office minister Tobias Ellwood told reporters that the Russian pause was "being used simply for them to regroup and further their own stranglehold over Aleppo".
Referring to the air strikes, he said: "This is shameful and it is not the action or leadership that we expect from a P5 (permanent member of the UN Security Council) nation."
Ted Allegra, deputy US ambassador, said the Russian and Syrian assault had killed 400 people, including 100 children.
"These shocking acts in Aleppo beg for an appropriate investigation and those who commit them must be held accountable," he said.
Russian Ambassador Alexey Borodavkin accused Britain and its allies of "trying to save terrorists from being the target of strikes, allowing them to regroup and continue their barbaric acts".
An 11-hour unilateral ceasefire in Aleppo was "allowing civilians and those fighters who lay down their weapons to leave" the city, Moscow's envoy said.
Paulo Pinheiro, chairman of the UN commission of inquiry on Syria, said that the panel would continue to document war crimes in Aleppo and urged the government of President Bashar Al Assad to provide information on violations.
"Hospitals, markets, bakeries and water stations have all been targeted by airplanes flying overhead; many have been destroyed, amplifying the effect of the siege," he said.
Countering that, Syria's ambassador Hussam Aala accused countries of launching a "propaganda campaign" against his country.