Syria's regime and rebels were locked in fierce clashes Sunday on the western edges of Aleppo, where 38 civilians have been killed in two days of opposition rocket fire, a monitor said.
Among those killed over the two-day period were 14 children, said the Syrian Observatory for Human Rights.
Another 250 civilians have been wounded in heavy bombardment by anti-government factions since Friday morning, according to the Britain-based group.
The barrage is part of a major assault by rebels and allied jihadists to break a three-month government siege of Aleppo's eastern half, where more than 250,000 people still live.
"Rebel fighters have launched hundreds of rockets and shells onto the western districts from positions inside the city and on its western edges," said Observatory head Rami Abdel Rahman.
He said the rebels were trying to push east from Dahiyet al-Assad district -- most of which they seized in the first day of the onslaught -- towards Hamdaniyeh.
Hamdaniyeh is a regime-held district directly adjacent to opposition-controlled eastern neighbourhoods.
Fighting lasted all night and into Sunday morning, with air strikes and artillery fire along the western battlefronts heard even in the eastern districts, an AFP correspondent there said.
Plumes of smoke could be seen snaking up from the city's skyline.
The offensive has seen an estimated 1,500 opposition fighters mass on the western edges of Aleppo since Friday.
They include local Aleppo rebels and reinforcements from Idlib province to the west, among them the jihadist Fateh al-Sham Front, which changed its name from Al-
Nusra Front after breaking ties with Al-Qaeda.
Fighting has killed 30 regime and allied fighters, as well as 50 Syrian opposition militants, according to the Observatory.
The monitor did not have an immediate death toll for foreign anti-regime fighters, many of whom have joined jihadist factions.