At least 14 civilians, including seven children, were killed on Thursday when Syrian regime helicopters dropped barrel bombs on northern Aleppo province, a monitoring group told AFP.

The attacks came as part of an intensified air campaign over Aleppo in recent weeks, despite an international outcry over the civilian deaths.

In the village of Hayyan, north of Aleppo city, barrel bombs killed two elderly men, a woman, and five children from a single family, the Syrian Observatory for Human Rights said.

North of the provincial capital, six civilians — among them two children — were killed when barrel bombs were dropped on the village of Deir Jamal.

The Observatory, which relies on a network of activists and fighters, said many were critically wounded or still stuck under the rubble.

On May 31, barrel bombs dropped on rebel-controlled areas throughout Aleppo province killed more than 80 people, one of the highest daily tolls since the beginning of 2015, according to AFP.

UN’s Syria peace envoy Staffan de Mistura called the civilian deaths “totally unacceptable”.

For months, the regime has waged an unrelenting aerial campaign against the opposition-held part of the city, making particular use of crude so-called barrel bombs.

Rights groups have criticized the weapons as indiscriminate and said they are more likely to cause civilian casualties.

Amnesty International, in fact, recently accused Syrian government forces of committing “crimes against humanity” by indiscriminately bombing Aleppo.

Despite documentation of the government’s use of the weapons by rights groups and activists on the ground, Syrian President Bashar Al-Assad has repeatedly denied that his forces use barrel bombs.

In a recent interview, Assad asked “what are barrel bombs?” when asked about his army’s use of the weapon.

AFP contributed to this report.