London, Feb 6 (IANS/AKI): Children accounted for 73 out of at least 246 people killed by barrel bombs dropped by Syrian government forces on the northern city of Aleppo since the weekend, opposition activists said Thursday.

The London-based Syrian Observatory for Human Rights watchdog said hundreds of people had been injured in the "indiscriminate" barrel bomb attacks that began last Saturday on rebel-held eastern districts of the city.

The watchdog relies on a network of activists and doctors inside Syria.

The almost daily attacks in Aleppo have prompted a mass exodus from several districts in the east of the city that have been targeted by the bombings, according to witnesses.

Syria's Western-backed Syrian National Coalition, the main opposition bloc, Thursday accused the Syrian army of killing 15 children in a barrel bomb attack during lessons in a mosque in Aleppo and of having killed dozens in such attacks on mosques and schools.

US Secretary of State John Kerry Wednesday deplored the barrel bombings as the "latest barbaric act" by the government of President Bashar al-Assad, which he said was determined to inflict more destruction on the war-wracked country.

Kerry said the barrel bomb attacks "undermined hope" for successful peace talks in Geneva, which are due to resume between the Syrian government and the Western-backed main opposition bloc Feb 10.

The bombs are essentially oil drums or cylinders packed with explosives and metal fragments.

Syria’s conflict erupted in March 2011 after a crackdown on peaceful Arab Spring-inspired protests against the authoritarian Assad government.

The conflict has escalated into sectarian-tinged civil war estimated to have claimed over 130,000 lives and driven millions from their homes amid a devastating humanitarian crisis.