Residents in Syria's battleground city of Aleppo cowered indoors Saturday as fierce air strikes toppled buildings and killed at least 45 civilians, after diplomatic efforts to revive a ceasefire failed.
Nearly two million civilians were left without water in the devastated northern city after regime bombardment damaged a pumping station and rebels shut down another in retaliation, the United Nations said.
UN Secretary-General Ban Ki-moon said he was "appalled by the chilling military escalation in the city of Aleppo, which is facing the most sustained and intense bombardment since the start of the Syrian conflict".
"Since the announcement two days ago by the Syrian Army of an offensive to capture eastern Aleppo, there have been repeated reports of airstrikes involving the use of incendiary weapons and advanced munitions such as bunker buster bombs," he continued.
The statement came after Russian and regime airstrikes killed forty five civilians on Friday including several children in eastern Aleppo.
Voicing indignation, US Secretary of State John Kerry, who failed in talks this week with Russian counterpart Sergei Lavrov to revive a ceasefire said: "What is happening in Aleppo today is unacceptable. It is beyond the pale."
"If people are serious about wanting a peaceful outcome... they should cease and desist bombing innocent women and children, cease cutting off water and laying siege in mediaeval terms to an entire community," he said.
Kerry had harsh words for Moscow's involvement in the conflict, in comments at a meeting with his European counterparts.
"Russia needs to set an example, not a precedent -– an unacceptable precedent, I might add, for the entire world," he said.
"Breach of International humanitarian law"
Following the statement of the UN Secretary-General, top EU officials said that the attacks on civilians in Aleppo amount to a "breach of international humanitarian law."
"The indiscriminate suffering being caused among innocent civilians... is an unacceptable breach of international humanitarian law," EU foreign policy chief Federica Mogherini and humanitarian commissioner Christos Stylianides said in a statement.
They denounced the "fire-bombing and shelling" as well as the "deliberate targeting" of a humanitarian convoy last week and the "cutting off of water supplies to the majority of civilians still in the city."
The aid convoy was hit by an airstrike that US officials have said was carried out by Russian planes backing regime leader Bashar al-Assad.
UN officials say nearly two million civilians were left without water in the devastated northern city after regime bombardment damaged a pumping station and rebels shut down another in retaliation.
In their statement, Mogherini and Stylianides called the suffering caused by the attacks "an affront" to the whole world.
"It risks to take us ever further from a negotiated settlement of the conflict, which remains the only way of bringing it to an end," they added.
The pair called on those with influence on the regime and those dealing with the armed opposition "to apply the maximum pressure to cease the attacks."
They also urged them to work to "allow unhindered and continuous humanitarian access to those in need, and resume political negotiations under the auspices of the UN in Geneva as swiftly as possible."
Meanwhile, Britain, France and the United States have requested an urgent UN Security Council meeting on the escalating campaign in Syria's second city of Aleppo, diplomats said Saturday.
The meeting was likely to be held at 1400 GMT on Sunday, the diplomats said.
The approximately 250,000 people in east Aleppo have been under near-continuous siege since government troops encircled the area in mid-July.