At least 43 civilians have been killed in tit-for-tat attacks by rebels and Syrian regime forces in the northern city of Aleppo, a monitoring group reported on Saturday.
The toll included 34 civilians killed late Friday in shelling attacks by rebels on regime-controlled areas in Aleppo, the Syrian Observatory for Human Rights said.
The shelling left more than 200 injured, according to the Britain-based watchdog that relies on a network of activists inside Syria.
Meanwhile, at least nine civilians, including six children, were killed in shelling and airstrikes by regime forces on rebel-held areas in Aleppo, the observatory said.
Forces loyal to Syrian President Bashar al-Assad on Saturday pressed ahead with their bombardment on and near the strategic Castello Road, the only supply route to the rebel-held areas in Aleppo.
Should government forces dislodge the opposition from the area around Aleppo, they would impose a siege on the city.
There are an estimated 250,000 to 300,000 people living in the rebel-held areas of Aleppo.
Once Syria's commercial hub, Aleppo has been divided between al-Assad's forces in the west and rebels in the east since fighting erupted for control of the city in mid-2012.