Russia has criticised the US and UK for using “unacceptable” tone and rhetoric in speeches on Syria at the UN, after being accused of “barbarism“.
US permanent representative Samantha Power said Russian and Syrian forces were “laying waste” to besieged rebel-held areas of the city of Aleppo.
Kremlin spokesman Dmitry Peskov warned that such language might damage efforts to end the five-year civil war.
Activists meanwhile reported dozens of fresh air strikes on Aleppo overnight.
The Syrian Observatory for Human Rights said at least two civilians had been killed, while a rescue worker accused the Syrian and Russian air forces of using munitions containing phosphorus and napalm, and cluster bombs.
At least 124 people are believed to have been killed in rebel-held Aleppo since last week, when a truce brokered by the US and Russia collapsed and the Syrian military announced the start of an operation to take full control of the city.
The US, UK and France, which back the opposition to Syrian President Bashar al-Assad, openly accused Russia of lying about its involvement in the assault on Aleppo at an emergency session of the UN Security Council.
British permanent representative Matthew Rycroft said Mr Assad’s forces and Moscow had He alleged that they were committing war crimes by using “bunker-busting bombs to destroy underground shelters, dropping incendiary weapons indiscriminately on civilian areas, and targeting the city’s water supplies”.
Ms Power told the meeting: “Instead of pursuing peace, Russia and Assad make war. Instead of helping get life-saving aid to civilians, Russia and Assad are bombing the humanitarian convoys, hospitals, and first responders who are trying desperately to keep people alive.”
“What Russia is sponsoring and doing is not counterterrorism; it is barbarism,” she added.