"From December 15 to 22, 301 people have been killed, including 87 children, 30 women and 30 rebels," said the Syrian Observatory for Human Rights, which relies on a network of activists and witnesses on the ground to track the civil war.
Opponents of Syrian President Bashar al-Assad accuse his forces of dropping explosives-filled barrels on rebel-held areas in an effort to demoralise their supporters and turn them against the insurgents.
Aleppo has been split between opposition and government forces since a massive rebel assault in the summer of 2012.
Human Rights Watch has accused government forces of using weapons and tactics that fail to distinguish between civilians and combatants, making such attacks "unlawful".
Yesterday the main opposition National Coalition called on Western states to impose a no-fly zone to halt such attacks.
"Until Assad's warplanes are stopped, the humanitarian disaster, regional instability, and the rise of extremism will only continue to get worse," Munzer Aqbiq, an adviser to the Coalition's president, said in a statement.