The source, who spoke anonymously due to fears of reprisal, said 15 civilians had been killed in three separate airstrikes that targeted a busy market in the town of Al-Rastan on Homs’ northern outskirts.

Due to a chronic shortfall of medical equipment, those injured by the strikes could not be treated at a local field hospital and were taken instead to the nearby town of Talbiseh.

The same source said a separate round of airstrikes in Idlib’s town of Ariha had left another 13 dead and 22 injured.

Syria has been locked in a vicious civil war since early 2011, when the Assad regime cracked down on pro-democracy protests with unexpected ferocity.

According to the Syrian Center for Policy Research, an NGO, as many as 470,000 people have been killed over the course of the five-year-long conflict.