Story highlights Syrian forces have dropped barrel bombs on Aleppo schools, hospitals, mosques and markets, Amnesty International says

Atrocities by government forces and opposition groups have made life for civilians "increasingly unbearable," it reports

In a media interview this year, Syrian President Bashar al-Assad denied that his forces used barrel bombs

(CNN) Syrian government forces have caused death and devastating injuries to civilians by dropping barrel bombs on schools, hospitals, mosques and crowded markets in opposition-controlled areas of Aleppo, rights group Amnesty International has alleged in a new report.

Attacks using barrel bombs -- oil drums filled with explosives and shrapnel and dropped by aircraft -- killed more than 3,000 civilians in Aleppo governorate last year, the report said, and have helped create a climate of fear.

Many terrified Aleppo residents have resorted to eking out a subterranean existence to try to stay alive, Amnesty International said, with many hospitals also moving underground in opposition-controlled areas of the northern city.

Its report also accuses armed opposition groups of carrying out appalling human rights violations against civilians.

"Widespread atrocities, in particular the vicious and unrelenting aerial bombardment of civilian neighbourhoods by government forces, have made life for civilians in Aleppo increasingly unbearable," said Philip Luther, director of Amnesty International's Middle East and North Africa program.

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