Up to 10 people have been killed in airstrikes on the northern city, once the nation's commercial capital. A political solution to end the five-year conflict remains elusive as peace talks and a ceasefire crumble.
The UK-based Syrian Observatory for Human Rights on Friday reported that 10 people were killed or injured in Aleppo following an aerial bombardment.
A member of the local civil defense told AFP news agency that at least seven people were killed and 10 people wounded, though the death toll was expected to rise as emergency response teams searched for survivors.
The Observatory reported that three civilians were also killed in airstrikes, claiming these were conducted by "regime forces."
The uptick in violence comes as peace talks in Geneva have unraveled, with the Saudi-backed opposition alliance High Negotiations Committee (HNC) suspending their participation, citing repeated ceasefire violations.
On February 27, a US-Russia brokered "cessation of hostilities" between government forces and rebels groups vying to overthrow President Bashar al-Assad went into effect, although the "Islamic State" and al-Nusra Front militant groups were not included in the truce.
Russia: in or out?
Ben Rhodes, the US deputy national security adviser, on Thursday said Washington is "concerned about reports of Russia moving [military] material into Syria."
In a surprise move, Moscow in March announced it would partially withdraw its forces from Syria, where it has conducted airstrikes against "terrorist" targets, although rebels groups and rights organizations accused Russia of propping up Assad's regime.
"It would be negative for Russia to move additional military equipment or personnel into Syria. We believe that our efforts are best focused on supporting the diplomatic process," Rhodes added.
The HNC on Friday reiterated its demand that al-Assad be excluded from any political solution to end the five year civil war.
"Assad must go for there to be lasting peace in Syria," the HNC wrote in a tweet.
More than 270,000 people have been killed since government forces launched a violent crackdown on pro-democracy protesters demanding al-Assad's ouster in 2011. Since then, a multi-front conflict has displaced around half of Syria's population, according to UN figures.