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”.
On Sunday, 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, a UK-based monitoring group, said at least two civilians had been killed and many wounded.
At least 128 people are believed to have died in rebel-held Aleppo since last week, when a truce brokered by the US and Russia collapsed.