UN peace envoy to Syria Staffan de Mistura on Sunday strongly condemned deadly rocket attacks by rebels targeting civilian areas in western Aleppo.
"Credible reports... indicate that scores of civilians in west Aleppo have been killed, including several children, and hundreds wounded due to relentless and indiscriminate attacks from armed opposition groups," De Mistura's office said in a statement.
"(The envoy) is appalled and shocked by the high number of rockets indiscriminately launched by armed opposition groups on civilian suburbs of western Aleppo in the last 48 hours."
De Mistura's statement came as regime forces were locked in fierce fighting on Aleppo's western edges, where the Syrian Observatory for Human Rights says 38 civilians have been killed in an opposition offensive to break a government siege.
"Those who argue that this is meant to relieve the siege of eastern Aleppo should be reminded that nothing justifies the use of disproportionate and indiscriminate weapons, including heavy ones, on civilian areas and it could amount to war crimes," De Mistura said.
The envoy meanwhile condemned attacks on schools on both sides, as well as air strikes on civilian areas.
"The civilians of both sides of Aleppo have suffered enough due to futile but lethal attempts of subduing the city of Aleppo," he said.