Damascus: Syrian opposition fighters launched a major assault on government-held districts of Aleppo city on Monday after the regime severed their only remaining supply route into the city, an AFP correspondent said.
The multi-front assault was also reported by the Syrian Observatory for Human Rights, a Britain-based monitor.
The attack was accompanied by a barrage of rocket fire into the regime-held west of the city, which killed at least eight people, said state media.
The offensive began at dawn, sparking heavy clashes between regime and rebel forces along the frontline that divides the government-held west and opposition-held east of Aleppo, the AFP correspondent said.
"Opposition factions launched a wide-scale attack on four fronts against the regime inside Aleppo city, including in the Old City," said Observatory chief Rami Abdel Rahman.
"There is currently fierce fighting underway, but the opposition has not advanced because of the heavy aerial bombardment the regime is carrying out on the areas where fighting is underway," he added.
There was no immediate toll for either side in the clashes.
The Observatory said rebels had also fired some 300 shells into western Aleppo since dawn, giving a toll of at least five dead in the bombardment.
State television said eight civilians had been killed and 80 people wounded in fire by "terrorist groups on residential neighbourhoods in Aleppo city".
Ahmed, a resident of western Aleppo, said the shelling had completely destroyed his home in the Syriac quarter.
"The shells have rained down on the western neighbourhoods since 4:30 am," he told AFP.
Residents of the neigbourhood gathered in one of the affected areas on Monday morning, lifting debris and helping locals gather their belongings so they could leave in search of shelter elsewhere.
"The sounds of the fighting can still be heard and are very loud, and the shelling on the western neighbourhoods is ongoing," he said.
The assault came a day after a failed rebel bid to push regime forces back from the key Castello Road supply route that leads into opposition-held Aleppo.
The route was the only remaining road into the east of the city, and was effectively severed on Thursday when regime troops took a hilltop within firing range.
The failed bid to push government forces back from the road killed at least 29 rebel fighters, said the Observatory.
Once Syria`s economic powerhouse, Aleppo city has been ravaged by the fighting that began there in mid-2012.
The city has been divided between regime and rebel control since then, with the frontline inside Aleppo remaining mostly static.
More than 280,000 people have been killed since the Syrian conflict began in March 2011 with anti-government protests that were met with a fierce crackdown.