AT LEAST 26 civilians have died in fresh government air strikes on Syria’s contested city of Aleppo, as the United Nations Security Council convened an emergency meeting on the violence but failed to take any action because of deep divisions between Russia and the Western powers.

The US, Britain and France, who called the meeting, heaped blame on Moscow for supporting the Syrian offensive, which UN envoy Staffan de Mistura called one of the worst of the five-year war.

When Syria’s UN ambassador Bashar Ja’afari was called to speak in the council, the ambassadors of the three Western powers walked out in protest.

They had demanded a halt to the Aleppo offensive and immediate council action and their walkout demonstrated anger and frustration not only at Damascus but at Russia for backing close ally Bashar al-Assad’s military campaign while talking about reviving a cessation of hostilities.

“What Russia is sponsoring and doing is not counter-terrorism, it’s barbarism,” said US ambassador Samantha Power. “It’s apocalyptic what is being done in eastern Aleppo.”

As the government offensive entered its fourth day on Sunday, air strikes were reported on neighbourhoods throughout Aleppo’s rebel-held eastern districts.

The British-based Syrian Observatory for Human Rights reported that 26 civilians had been killed by 7.30pm and said it expected the toll to rise.

Ibrahim Alhaj of the Syrian Civil Defence search-and-rescue group gave a higher toll, saying hospitals and rescuers had documented the deaths of 43 people.

The observatory said earlier that 213 civilians had been killed by air strikes and shelling on opposition areas in and around Aleppo since the US-Russian brokered ceasefire collapsed last Monday.

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 that oversees medical affairs in the city’s opposition quarters. “I’ve never seen so many people dying in once place,” he said.

Russia’s UN ambassador Vitaly Churkin blamed Syria’s rebels for sabotaging the ceasefire agreement by using the lull to shore up their forces, and accused the Western coalition of failing to separate the moderate factions it backs from “terrorist” groups, especially the al-Qaeda-linked Fatah Sham Front.

“In Syria, hundreds of armed groups are being armed,” Churkin said. “The territory of the country is being bombed indiscriminately. Bringing a peace is almost an impossible task now.”

But he made clear that Moscow had not given up on a cessation of hostilities.

Power said the United States knew “that Russia has consistently said one thing, and done the opposite”, but said the US also believed it must do “everything in [its] power to find a way to halt the violence”.

A broad coalition of 33 Syrian rebel factions issued a statement on Sunday saying: “Negotiations under the present conditions are no longer useful and are meaningless.”

The opposition groups said they would not accept any Russian mediation, calling Moscow a “partner to the regime in the crimes against our people”.