At least 20 people have been killed in Syrian government air strikes in Aleppo city while 30 others have been injured, according to the Syrian Observatory for Human Rights.
The government has been accused of dropping barrel bombs on Jisr al-Haj, a neighbourhood in Aleppo, in an attack Syrian activists called a massacre on Tuesday.
The UK-based Syrian Observatory, a network of activists, reported that among those injured many were in critical health conditions. The majority of those killed in the attack were burnt to death.
Elsewhere in Syria, the Syrian Observatory said, at least 30 people were killed and 27 others were injured in two suicide attacks in Wadi al-Zahab and al-Arman in Homs province.
The two neighbourhoods are known to be inhabited by mostly Alawites.
In the past four months, more than 11,000 air strikes were carried out by the Syrian regime, the Syrian Observatory reported, including 5,943 barrel bombs.
Al Jazeera could not independently verify the Syrian Observatory's reports.
Death everywhere: War crimes and human rights abuses in Aleppo
The death toll due to air strikes and barrel bombs is over 1,600 civilians while 13,000 others were injured.
A report released by the rights monitor Amnesty International, titled Death everywhere: War crimes and human rights abuses in Aleppo, details war crimes and other abuses being committed in the city by government forces and armed opposition groups on a daily basis.
The report also concludes that some of the government's actions in Aleppo amount to crimes against humanity.
It says many civilians in Aleppo have been forced to eke out an existence underground to escape a relentless aerial bombardment of opposition-held areas by government forces.
Attacks using barrel bombs - oil barrels, fuel tanks or gas cylinders packed with explosives, fuel, and metal fragments dropped from helicopters - killed more than 3,000 civilians in Aleppo last year, and more than 11,000 in Syria since 2012, Amnesty International said.
Source: Al Jazeera